diff --git a/Config.h b/Config.h
index c8f1bf40..16d3db53 100644
--- a/Config.h
+++ b/Config.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#define NUKI_HUB_VERSION "8.32"
+#define NUKI_HUB_VERSION "8.33-pre-6"
 
 #define GITHUB_LATEST_RELEASE_URL "https://github.com/technyon/nuki_hub/releases/latest"
 #define GITHUB_LATEST_RELEASE_API_URL "https://api.github.com/repos/technyon/nuki_hub/releases/latest"
diff --git a/lib/espMqttClient/CMakeLists.txt b/lib/espMqttClient/CMakeLists.txt
new file mode 100644
index 00000000..37022275
--- /dev/null
+++ b/lib/espMqttClient/CMakeLists.txt
@@ -0,0 +1,17 @@
+set(COMPONENT_SRCDIRS
+    "src" "src/Packets" "src/Transport"
+)
+
+set(COMPONENT_ADD_INCLUDEDIRS
+    "src" "src/Packets" "src/Transport"
+)
+
+set(COMPONENT_REQUIRES
+    "arduino-esp32"
+    "AsyncTCP"
+)
+
+register_component()
+
+target_compile_definitions(${COMPONENT_TARGET} PUBLIC -DESP32)
+target_compile_options(${COMPONENT_TARGET} PRIVATE -fno-rtti)
diff --git a/lib/espMqttClient/README.md b/lib/espMqttClient/README.md
index 586d3339..28403067 100644
--- a/lib/espMqttClient/README.md
+++ b/lib/espMqttClient/README.md
@@ -15,12 +15,13 @@ Aims to be a non-blocking, fully compliant MQTT 3.1.1 client.
 - TCP and TCP/TLS using standard WiFiClient and WiFiClientSecure connections
 - Virtually unlimited incoming and outgoing payload sizes
 - Readable and understandable code
-- Fully async clients available via [AsyncTCP](https://github.com/me-no-dev/AsyncTCP) or [ESPAsnycTCP](https://github.com/me-no-dev/ESPAsyncTCP) (no TLS supported)
+- Fully async clients available via [AsyncTCP](https://github.com/esphome/AsyncTCP) or [ESPAsnycTCP](https://github.com/esphome/ESPAsyncTCP) (no TLS supported)
 - Supported platforms:
   - Espressif ESP8266 and ESP32 using the Arduino framework
+  - Espressif ESP32 using the ESP IDF, see [esp idf component](https://docs.espressif.com/projects/arduino-esp32/en/latest/esp-idf_component.html)
 - Basic Linux compatibility*. This includes WSL on Windows
 
-    > Linux compatibility is mainly for automatic testing. It relies on a quick and dirty Arduino-style `Client` with a POSIX TCP client underneath and Arduino-style `IPAddress` class. These are lacking many features needed for proper Linux support.
+    > Linux compatibility is mainly for automatic testing. It relies on a quick and dirty Arduino-style `Client` with a POSIX TCP client underneath and Arduino-style `ClientPosixIPAddress` class. These are lacking many features needed for proper Linux support.
 
 # Documentation
 
diff --git a/lib/espMqttClient/component.mk b/lib/espMqttClient/component.mk
new file mode 100644
index 00000000..bb5bb161
--- /dev/null
+++ b/lib/espMqttClient/component.mk
@@ -0,0 +1,3 @@
+COMPONENT_ADD_INCLUDEDIRS := src
+COMPONENT_SRCDIRS := src
+CXXFLAGS += -fno-rtti
diff --git a/lib/espMqttClient/docs/index.md b/lib/espMqttClient/docs/index.md
index cae13f8a..077686b8 100644
--- a/lib/espMqttClient/docs/index.md
+++ b/lib/espMqttClient/docs/index.md
@@ -10,7 +10,7 @@
 - TCP and TCP/TLS using standard WiFiClient and WiFiClientSecure connections
 - Virtually unlimited incoming and outgoing payload sizes
 - Readable and understandable code
-- Fully async clients available via [AsyncTCP](https://github.com/me-no-dev/AsyncTCP) or [ESPAsnycTCP](https://github.com/me-no-dev/ESPAsyncTCP) (no TLS supported)
+- Fully async clients available via [AsyncTCP](https://github.com/esphome/AsyncTCP) or [ESPAsnycTCP](https://github.com/esphome/ESPAsyncTCP) (no TLS supported)
 - Supported platforms:
   - Espressif ESP8266 and ESP32 using the Arduino framework
 - Basic Linux compatibility*. This includes WSL on Windows
@@ -232,25 +232,25 @@ Add a publish acknowledged event handler. Function signature: `void(uint16_t pac
 bool connected()
 ```
 
-Returns if the client is currently fully connected to the broker or not. During connecting or disconnecting, it will return false.
+Returns `true` if the client is currently fully connected to the broker. During connecting or disconnecting, it will return `false`.
 
 ```cpp
 bool disconnected()
 ```
 
-Returns if the client is currently disconnected to the broker or not. During disconnecting or connecting, it will return false.
+Returns `true` if the client is currently disconnected from the broker. During disconnecting or connecting, it will return `false`.
 
 ```cpp
-void connect()
+bool connect()
 ```
 
-Connect to the server.
+Start the connect procedure. Returns `true` if successful. A positive return value doesn not mean the client is already connected.
 
 ```cpp
-void disconnect(bool force = false)
+bool disconnect(bool force = false)
 ```
 
-Disconnect from the server.
+Start the disconnect procedure, return `true` if successful. A positive return value doesn not mean the client is already disconnected.
 When disconnecting with `force` false, the client first tries to handle all the outgoing messages in the queue and disconnect cleanly afterwards. During this time, no incoming PUBLISH messages are handled.
 
 - **`force`**: Whether to force the disconnection. Defaults to `false` (clean disconnection).
@@ -341,10 +341,20 @@ const char* getClientId() const
 
 Retuns the client ID.
 
+```cpp
+size_t queueSize();
+```
+
+Returns the amount of elements, regardless of type, in the queue.
+
 # Compile time configuration
 
 A number of constants which influence the behaviour of the client can be set at compile time. You can set these options in the `Config.h` file or pass the values as compiler flags. Because these options are compile-time constants, they are used for all instances of `espMqttClient` you create in your program.
 
+### EMC_TX_TIMEOUT 10000
+
+Timeout in milliseconds before a (qos > 0) message will be retransmitted.
+
 ### EMC_RX_BUFFER_SIZE 1440
 
 The client copies incoming data into a buffer before parsing. This sets the buffer size.
@@ -388,6 +398,10 @@ The (maximum) length of the client ID. (Keep in mind that this is a c-string. Yo
 
 Only used on ESP32. Sets the stack size (in words) of the MQTT client worker task.
 
+### EMC_MULTIPLE_CALLBACKS
+
+This macro is by default not enabled so you can add a single callbacks to an event. Assigning a second will overwrite the existing callback. When enabling multiple callbacks, multiple callbacks (with uint32_t id) can be assigned. Removing is done by referencing the id.
+
 ### EMC_USE_WATCHDOG 0
 
 (ESP32 only)
diff --git a/lib/espMqttClient/examples/notask-esp32/notask-esp32.ino b/lib/espMqttClient/examples/notask-esp32/notask-esp32.ino
new file mode 100644
index 00000000..27bc675d
--- /dev/null
+++ b/lib/espMqttClient/examples/notask-esp32/notask-esp32.ino
@@ -0,0 +1,148 @@
+#include <WiFi.h>
+
+#include <espMqttClient.h>
+
+#define WIFI_SSID "yourSSID"
+#define WIFI_PASSWORD "yourpass"
+
+#define MQTT_HOST IPAddress(192, 168, 1, 10)
+#define MQTT_PORT 1883
+
+espMqttClient mqttClient(espMqttClientTypes::UseInternalTask::NO);
+bool reconnectMqtt = false;
+uint32_t lastReconnect = 0;
+
+void connectToWiFi() {
+  Serial.println("Connecting to Wi-Fi...");
+  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
+}
+
+void connectToMqtt() {
+  Serial.println("Connecting to MQTT...");
+  if (!mqttClient.connect()) {
+    reconnectMqtt = true;
+    lastReconnect = millis();
+    Serial.println("Connecting failed.");
+  } else {
+    reconnectMqtt = false;
+  }
+}
+
+void WiFiEvent(WiFiEvent_t event) {
+  Serial.printf("[WiFi-event] event: %d\n", event);
+  switch(event) {
+  case SYSTEM_EVENT_STA_GOT_IP:
+    Serial.println("WiFi connected");
+    Serial.println("IP address: ");
+    Serial.println(WiFi.localIP());
+    connectToMqtt();
+    break;
+  case SYSTEM_EVENT_STA_DISCONNECTED:
+    Serial.println("WiFi lost connection");
+    break;
+  default:
+    break;
+  }
+}
+
+void onMqttConnect(bool sessionPresent) {
+  Serial.println("Connected to MQTT.");
+  Serial.print("Session present: ");
+  Serial.println(sessionPresent);
+  uint16_t packetIdSub = mqttClient.subscribe("foo/bar", 2);
+  Serial.print("Subscribing at QoS 2, packetId: ");
+  Serial.println(packetIdSub);
+  mqttClient.publish("foo/bar", 0, true, "test 1");
+  Serial.println("Publishing at QoS 0");
+  uint16_t packetIdPub1 = mqttClient.publish("foo/bar", 1, true, "test 2");
+  Serial.print("Publishing at QoS 1, packetId: ");
+  Serial.println(packetIdPub1);
+  uint16_t packetIdPub2 = mqttClient.publish("foo/bar", 2, true, "test 3");
+  Serial.print("Publishing at QoS 2, packetId: ");
+  Serial.println(packetIdPub2);
+}
+
+void onMqttDisconnect(espMqttClientTypes::DisconnectReason reason) {
+  Serial.printf("Disconnected from MQTT: %u.\n", static_cast<uint8_t>(reason));
+
+  if (WiFi.isConnected()) {
+    reconnectMqtt = true;
+    lastReconnect = millis();
+  }
+}
+
+void onMqttSubscribe(uint16_t packetId, const espMqttClientTypes::SubscribeReturncode* codes, size_t len) {
+  Serial.println("Subscribe acknowledged.");
+  Serial.print("  packetId: ");
+  Serial.println(packetId);
+  for (size_t i = 0; i < len; ++i) {
+    Serial.print("  qos: ");
+    Serial.println(static_cast<uint8_t>(codes[i]));
+  }
+}
+
+void onMqttUnsubscribe(uint16_t packetId) {
+  Serial.println("Unsubscribe acknowledged.");
+  Serial.print("  packetId: ");
+  Serial.println(packetId);
+}
+
+void onMqttMessage(const espMqttClientTypes::MessageProperties& properties, const char* topic, const uint8_t* payload, size_t len, size_t index, size_t total) {
+  (void) payload;
+  Serial.println("Publish received.");
+  Serial.print("  topic: ");
+  Serial.println(topic);
+  Serial.print("  qos: ");
+  Serial.println(properties.qos);
+  Serial.print("  dup: ");
+  Serial.println(properties.dup);
+  Serial.print("  retain: ");
+  Serial.println(properties.retain);
+  Serial.print("  len: ");
+  Serial.println(len);
+  Serial.print("  index: ");
+  Serial.println(index);
+  Serial.print("  total: ");
+  Serial.println(total);
+}
+
+void onMqttPublish(uint16_t packetId) {
+  Serial.println("Publish acknowledged.");
+  Serial.print("  packetId: ");
+  Serial.println(packetId);
+}
+
+void setup() {
+  Serial.begin(115200);
+  Serial.println();
+  Serial.println();
+
+  WiFi.setAutoConnect(false);
+  WiFi.setAutoReconnect(true);
+  WiFi.onEvent(WiFiEvent);
+
+  mqttClient.onConnect(onMqttConnect);
+  mqttClient.onDisconnect(onMqttDisconnect);
+  mqttClient.onSubscribe(onMqttSubscribe);
+  mqttClient.onUnsubscribe(onMqttUnsubscribe);
+  mqttClient.onMessage(onMqttMessage);
+  mqttClient.onPublish(onMqttPublish);
+  mqttClient.setServer(MQTT_HOST, MQTT_PORT);
+
+  connectToWiFi();
+}
+
+void loop() {
+  static uint32_t currentMillis = millis();
+
+  if (reconnectMqtt && currentMillis - lastReconnect > 5000) {
+    connectToMqtt();
+  }
+
+  // We used to option not to use the internal task
+  // so we need to call the loop-method ourselves.
+  // During connecting it may block.
+  // Creating a separate task yourself is obviously
+  // also a possibility.
+  mqttClient.loop();
+}
diff --git a/lib/espMqttClient/examples/simple-esp32-idf/CMakeLists.txt b/lib/espMqttClient/examples/simple-esp32-idf/CMakeLists.txt
new file mode 100644
index 00000000..e1f4c038
--- /dev/null
+++ b/lib/espMqttClient/examples/simple-esp32-idf/CMakeLists.txt
@@ -0,0 +1,8 @@
+# The following lines of boilerplate have to be in your project's
+# CMakeLists in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.5)
+
+SET(SDKCONFIG ${CMAKE_BINARY_DIR}/sdkconfig)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(simple-esp32-idf)
\ No newline at end of file
diff --git a/lib/espMqttClient/examples/simple-esp32-idf/README.md b/lib/espMqttClient/examples/simple-esp32-idf/README.md
new file mode 100644
index 00000000..8fd90c7a
--- /dev/null
+++ b/lib/espMqttClient/examples/simple-esp32-idf/README.md
@@ -0,0 +1,3 @@
+This example is for use with [Arduino as a component](https://espressif-docs.readthedocs-hosted.com/projects/arduino-esp32/en/latest/esp-idf_component.html) in the ESP-IDF framework.
+
+Be sure to follow [this section](https://espressif-docs.readthedocs-hosted.com/projects/arduino-esp32/en/latest/esp-idf_component.html#adding-local-library) about adding libraries to your project.
diff --git a/lib/espMqttClient/examples/simple-esp32-idf/main/CMakeLists.txt b/lib/espMqttClient/examples/simple-esp32-idf/main/CMakeLists.txt
new file mode 100644
index 00000000..475d0f78
--- /dev/null
+++ b/lib/espMqttClient/examples/simple-esp32-idf/main/CMakeLists.txt
@@ -0,0 +1,3 @@
+idf_component_register(
+    SRCS "main.cpp"
+    INCLUDE_DIRS "")
\ No newline at end of file
diff --git a/lib/espMqttClient/examples/simple-esp32-idf/main/main.cpp b/lib/espMqttClient/examples/simple-esp32-idf/main/main.cpp
new file mode 100644
index 00000000..88334904
--- /dev/null
+++ b/lib/espMqttClient/examples/simple-esp32-idf/main/main.cpp
@@ -0,0 +1,142 @@
+#include <Arduino.h>
+#include <WiFi.h>
+
+#include <espMqttClient.h>
+
+#define WIFI_SSID "yourSSID"
+#define WIFI_PASSWORD "yourpass"
+
+#define MQTT_HOST IPAddress(192, 168, 1, 10)
+#define MQTT_PORT 1883
+
+espMqttClient mqttClient;
+bool reconnectMqtt = false;
+uint32_t lastReconnect = 0;
+
+void connectToWiFi() {
+  Serial.println("Connecting to Wi-Fi...");
+  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
+}
+
+void connectToMqtt() {
+  Serial.println("Connecting to MQTT...");
+  if (!mqttClient.connect()) {
+    reconnectMqtt = true;
+    lastReconnect = millis();
+    Serial.println("Connecting failed.");
+  } else {
+    reconnectMqtt = false;
+  }
+}
+
+void WiFiEvent(WiFiEvent_t event) {
+  Serial.printf("[WiFi-event] event: %d\n", event);
+  switch(event) {
+  case SYSTEM_EVENT_STA_GOT_IP:
+    Serial.println("WiFi connected");
+    Serial.println("IP address: ");
+    Serial.println(WiFi.localIP());
+    connectToMqtt();
+    break;
+  case SYSTEM_EVENT_STA_DISCONNECTED:
+    Serial.println("WiFi lost connection");
+    break;
+  default:
+    break;
+  }
+}
+
+void onMqttConnect(bool sessionPresent) {
+  Serial.println("Connected to MQTT.");
+  Serial.print("Session present: ");
+  Serial.println(sessionPresent);
+  uint16_t packetIdSub = mqttClient.subscribe("foo/bar", 2);
+  Serial.print("Subscribing at QoS 2, packetId: ");
+  Serial.println(packetIdSub);
+  mqttClient.publish("foo/bar", 0, true, "test 1");
+  Serial.println("Publishing at QoS 0");
+  uint16_t packetIdPub1 = mqttClient.publish("foo/bar", 1, true, "test 2");
+  Serial.print("Publishing at QoS 1, packetId: ");
+  Serial.println(packetIdPub1);
+  uint16_t packetIdPub2 = mqttClient.publish("foo/bar", 2, true, "test 3");
+  Serial.print("Publishing at QoS 2, packetId: ");
+  Serial.println(packetIdPub2);
+}
+
+void onMqttDisconnect(espMqttClientTypes::DisconnectReason reason) {
+  Serial.printf("Disconnected from MQTT: %u.\n", static_cast<uint8_t>(reason));
+
+  if (WiFi.isConnected()) {
+    reconnectMqtt = true;
+    lastReconnect = millis();
+  }
+}
+
+void onMqttSubscribe(uint16_t packetId, const espMqttClientTypes::SubscribeReturncode* codes, size_t len) {
+  Serial.println("Subscribe acknowledged.");
+  Serial.print("  packetId: ");
+  Serial.println(packetId);
+  for (size_t i = 0; i < len; ++i) {
+    Serial.print("  qos: ");
+    Serial.println(static_cast<uint8_t>(codes[i]));
+  }
+}
+
+void onMqttUnsubscribe(uint16_t packetId) {
+  Serial.println("Unsubscribe acknowledged.");
+  Serial.print("  packetId: ");
+  Serial.println(packetId);
+}
+
+void onMqttMessage(const espMqttClientTypes::MessageProperties& properties, const char* topic, const uint8_t* payload, size_t len, size_t index, size_t total) {
+  (void) payload;
+  Serial.println("Publish received.");
+  Serial.print("  topic: ");
+  Serial.println(topic);
+  Serial.print("  qos: ");
+  Serial.println(properties.qos);
+  Serial.print("  dup: ");
+  Serial.println(properties.dup);
+  Serial.print("  retain: ");
+  Serial.println(properties.retain);
+  Serial.print("  len: ");
+  Serial.println(len);
+  Serial.print("  index: ");
+  Serial.println(index);
+  Serial.print("  total: ");
+  Serial.println(total);
+}
+
+void onMqttPublish(uint16_t packetId) {
+  Serial.println("Publish acknowledged.");
+  Serial.print("  packetId: ");
+  Serial.println(packetId);
+}
+
+void setup() {
+  Serial.begin(115200);
+  Serial.println();
+  Serial.println();
+
+  WiFi.setAutoConnect(false);
+  WiFi.setAutoReconnect(true);
+  WiFi.onEvent(WiFiEvent);
+
+  mqttClient.onConnect(onMqttConnect);
+  mqttClient.onDisconnect(onMqttDisconnect);
+  mqttClient.onSubscribe(onMqttSubscribe);
+  mqttClient.onUnsubscribe(onMqttUnsubscribe);
+  mqttClient.onMessage(onMqttMessage);
+  mqttClient.onPublish(onMqttPublish);
+  mqttClient.setServer(MQTT_HOST, MQTT_PORT);
+
+  connectToWiFi();
+}
+
+void loop() {
+  static uint32_t currentMillis = millis();
+
+  if (reconnectMqtt && currentMillis - lastReconnect > 5000) {
+    connectToMqtt();
+  }
+}
diff --git a/lib/espMqttClient/examples/simple-esp32-idf/sdkconfig.defaults b/lib/espMqttClient/examples/simple-esp32-idf/sdkconfig.defaults
new file mode 100644
index 00000000..4661ad26
--- /dev/null
+++ b/lib/espMqttClient/examples/simple-esp32-idf/sdkconfig.defaults
@@ -0,0 +1,39 @@
+#
+# Bootloader config
+#
+CONFIG_BOOTLOADER_COMPILER_OPTIMIZATION_SIZE=y
+CONFIG_BOOTLOADER_LOG_LEVEL_NONE=y
+CONFIG_BOOTLOADER_LOG_LEVEL=0
+
+#
+# Serial flasher config
+#
+CONFIG_ESPTOOLPY_FLASHMODE_DIO=y
+CONFIG_ESPTOOLPY_FLASHMODE="dio"
+CONFIG_ESPTOOLPY_FLASHFREQ_40M=y
+CONFIG_ESPTOOLPY_FLASHFREQ="40m"
+CONFIG_ESPTOOLPY_FLASHSIZE_4MB=y
+CONFIG_ESPTOOLPY_FLASHSIZE="4MB"
+#
+# Partition Table
+#
+CONFIG_PARTITION_TABLE_CUSTOM=n
+
+#
+# Arduino Configuration
+#
+CONFIG_ARDUINO_VARIANT="esp32"
+CONFIG_ENABLE_ARDUINO_DEPENDS=y
+CONFIG_AUTOSTART_ARDUINO=y
+
+#
+# FreeRTOS
+#
+# 1000 require for Arduino
+CONFIG_FREERTOS_HZ=1000
+
+#ASYNC_TCP
+CONFIG_ASYNC_TCP_RUN_NO_AFFINITY=y
+
+#MBEDTLS
+CONFIG_MBEDTLS_PSK_MODES=y
\ No newline at end of file
diff --git a/lib/espMqttClient/keywords.txt b/lib/espMqttClient/keywords.txt
index 136da0af..3807482b 100644
--- a/lib/espMqttClient/keywords.txt
+++ b/lib/espMqttClient/keywords.txt
@@ -44,6 +44,7 @@ publish	KEYWORD2
 clearQueue	KEYWORD2
 loop	KEYWORD2
 getClientId	KEYWORD2
+queueSize KEYWORD2
 
 # Structures (KEYWORD3)
 espMqttClientTypes	KEYWORD3
diff --git a/lib/espMqttClient/library.json b/lib/espMqttClient/library.json
index b883dda5..ad44295b 100644
--- a/lib/espMqttClient/library.json
+++ b/lib/espMqttClient/library.json
@@ -14,21 +14,21 @@
     "type": "git",
     "url": "https://github.com/bertmelis/espMqttClient.git"
   },
-  "version": "1.4.2",
+  "version": "1.6.0",
   "frameworks": "arduino",
   "platforms": ["espressif8266", "espressif32"],
   "headers": ["espMqttClient.h", "espMqttClientAsync.h"],
   "dependencies": [
     {
-      "owner": "me-no-dev",
-      "name": "ESPAsyncTCP",
-      "version": ">=1.2.2",
+      "owner": "esphome",
+      "name": "ESPAsyncTCP-esphome",
+      "version": ">=2.0.0",
       "platforms": "espressif8266"
     },
     {
-      "owner": "me-no-dev",
-      "name": "AsyncTCP",
-      "version": ">=1.1.1",
+      "owner": "esphome",
+      "name": "AsyncTCP-esphome",
+      "version": ">=2.1.1",
       "platforms": "espressif32"
     }
   ],
diff --git a/lib/espMqttClient/library.properties b/lib/espMqttClient/library.properties
index f80a2ebb..55d488a0 100644
--- a/lib/espMqttClient/library.properties
+++ b/lib/espMqttClient/library.properties
@@ -1,5 +1,5 @@
 name=espMqttClient
-version=1.4.2
+version=1.6.0
 author=Bert Melis
 maintainer=Bert Melis
 sentence=an MQTT client for the Arduino framework for ESP8266 / ESP32
diff --git a/lib/espMqttClient/platformio.ini b/lib/espMqttClient/platformio.ini
index 43e3953c..77f8f5c9 100644
--- a/lib/espMqttClient/platformio.ini
+++ b/lib/espMqttClient/platformio.ini
@@ -19,6 +19,7 @@ build_flags =
   -Wextra
   -std=c++11
   -pthread
+  -ggdb3
 
 [env:native]
 platform = native
@@ -29,5 +30,13 @@ build_flags =
   --coverage
   -D EMC_RX_BUFFER_SIZE=100
   -D EMC_TX_BUFFER_SIZE=10
+  -D EMC_MULTIPLE_CALLBACKS=1
 ;extra_scripts = test-coverage.py
 build_type = debug
+test_testing_command =
+  valgrind
+  --leak-check=full
+  --show-leak-kinds=all
+  --track-origins=yes
+  --error-exitcode=1
+  ${platformio.build_dir}/${this.__env__}/program
diff --git a/lib/espMqttClient/scripts/CI/build_examples_pio.sh b/lib/espMqttClient/scripts/CI/build_examples_pio.sh
deleted file mode 100644
index 4ef860c3..00000000
--- a/lib/espMqttClient/scripts/CI/build_examples_pio.sh
+++ /dev/null
@@ -1,50 +0,0 @@
-#!/bin/bash
-
-# already done by workflow
-#pip install -U platformio
-#platformio update
-#pio pkg install --global --library me-no-dev/AsyncTCP
-#pio pkg install --global --library EspAsyncTCP
-
-RED='\033[0;31m'
-GREEN='\033[0;32m'
-YELLOW='\033[0;33m'
-NC='\033[0m'
-
-lines=$(find ./examples/ -maxdepth 1 -mindepth 1 -type d)
-retval=0
-retvalpart=0
-while read line; do
-  if [[ "$line" != *esp8266 && "$line" != *esp32 && "$line" != *linux ]]; then
-    echo -e "========================== BUILDING $line =========================="
-    echo -e "${YELLOW}SKIPPING${NC}"
-    continue
-  fi
-  echo -e "========================== BUILDING $line =========================="
-  if [[ -e "$line/platformio.ini" ]]; then
-    output=$(platformio ci --lib="." --project-conf="$line/platformio.ini" $line 2>&1)
-    retvalpart=$?
-  else
-    if [[ "$line" == *esp8266 ]]; then
-      output=$(platformio ci --lib="." --project-conf="scripts/CI/platformio_esp8266.ini" $line 2>&1)
-      retvalpart=$?
-    else
-      output=$(platformio ci --lib="." --project-conf="scripts/CI/platformio_esp32.ini" $line 2>&1)
-      retvalpart=$?
-    fi
-    :
-  fi
-  if [ $retvalpart -ne 0 ]; then
-    echo "$output"
-    echo -e "Building $line ${RED}FAILED${NC}"
-    retval=1
-  else
-    echo -e "${GREEN}SUCCESS${NC}"
-  fi
-done <<< "$lines"
-
-# will be deleted together with container
-#pio pkg uninstall --global --library me-no-dev/AsyncTCP
-#pio pkg uninstall --global --library EspAsyncTCP
-
-exit "$retval"
diff --git a/lib/espMqttClient/scripts/CI/platformio_esp32.ini b/lib/espMqttClient/scripts/CI/platformio_esp32.ini
deleted file mode 100644
index 326891de..00000000
--- a/lib/espMqttClient/scripts/CI/platformio_esp32.ini
+++ /dev/null
@@ -1,19 +0,0 @@
-; PlatformIO Project Configuration File
-;
-;   Build options: build flags, source filter
-;   Upload options: custom upload port, speed and extra flags
-;   Library options: dependencies, extra library storages
-;   Advanced options: extra scripting
-;
-; Please visit documentation for the other options and examples
-; https://docs.platformio.org/page/projectconf.html
-
-[env:esp32]
-platform = espressif32
-board = lolin32
-framework = arduino
-build_flags =
-  ;-Werror
-  -Wall
-  -Wextra
-  -Werror
diff --git a/lib/espMqttClient/scripts/CI/platformio_esp8266.ini b/lib/espMqttClient/scripts/CI/platformio_esp8266.ini
deleted file mode 100644
index d523d278..00000000
--- a/lib/espMqttClient/scripts/CI/platformio_esp8266.ini
+++ /dev/null
@@ -1,19 +0,0 @@
-; PlatformIO Project Configuration File
-;
-;   Build options: build flags, source filter
-;   Upload options: custom upload port, speed and extra flags
-;   Library options: dependencies, extra library storages
-;   Advanced options: extra scripting
-;
-; Please visit documentation for the other options and examples
-; https://docs.platformio.org/page/projectconf.html
-
-[env:esp8266]
-platform = espressif8266
-board = d1_mini
-framework = arduino
-build_flags =
-  ;-Werror
-  -Wall
-  -Wextra
-  -Werror
diff --git a/lib/espMqttClient/src/Config.h b/lib/espMqttClient/src/Config.h
index aba77956..9c609117 100644
--- a/lib/espMqttClient/src/Config.h
+++ b/lib/espMqttClient/src/Config.h
@@ -9,7 +9,7 @@ the LICENSE file.
 #pragma once
 
 #ifndef EMC_TX_TIMEOUT
-#define EMC_TX_TIMEOUT 5000
+#define EMC_TX_TIMEOUT 10000
 #endif
 
 #ifndef EMC_RX_BUFFER_SIZE
@@ -29,7 +29,7 @@ the LICENSE file.
 #endif
 
 #ifndef EMC_MIN_FREE_MEMORY
-#define EMC_MIN_FREE_MEMORY 4096
+#define EMC_MIN_FREE_MEMORY 16384
 #endif
 
 #ifndef EMC_ESP8266_MULTITHREADING
@@ -53,6 +53,10 @@ the LICENSE file.
 #define EMC_TASK_STACK_SIZE 5120
 #endif
 
+#ifndef EMC_MULTIPLE_CALLBACKS
+#define EMC_MULTIPLE_CALLBACKS 0
+#endif
+
 #ifndef EMC_USE_WATCHDOG
 #define EMC_USE_WATCHDOG 0
 #endif
diff --git a/lib/espMqttClient/src/Helpers.h b/lib/espMqttClient/src/Helpers.h
index 4a19224b..05ab136d 100644
--- a/lib/espMqttClient/src/Helpers.h
+++ b/lib/espMqttClient/src/Helpers.h
@@ -16,7 +16,7 @@ the LICENSE file.
   #define EMC_SEMAPHORE_TAKE() xSemaphoreTake(_xSemaphore, portMAX_DELAY)
   #define EMC_SEMAPHORE_GIVE() xSemaphoreGive(_xSemaphore)
   #define EMC_GET_FREE_MEMORY() std::max(ESP.getMaxAllocHeap(), ESP.getMaxAllocPsram())
-  #define EMC_YIELD() taskYIELD()
+  #define EMC_YIELD() vTaskDelay(1)
   #define EMC_GENERATE_CLIENTID(x) snprintf(x, EMC_CLIENTID_LENGTH, "esp32%06llx", ESP.getEfuseMac());
 #elif defined(ARDUINO_ARCH_ESP8266)
   #include <Arduino.h>  // millis(), ESP.getFreeHeap();
diff --git a/lib/espMqttClient/src/Logging.h b/lib/espMqttClient/src/Logging.h
index a1d85fa8..3ba096a8 100644
--- a/lib/espMqttClient/src/Logging.h
+++ b/lib/espMqttClient/src/Logging.h
@@ -10,6 +10,8 @@ the LICENSE file.
 
 #if defined(ARDUINO_ARCH_ESP32)
   #include <esp32-hal-log.h>
+  #include "freertos/FreeRTOS.h"
+  #include "freertos/task.h"
   #if defined(DEBUG_ESP_MQTT_CLIENT)
   // Logging is en/disabled by Arduino framework macros
     #define emc_log_i(...) log_i(__VA_ARGS__)
diff --git a/lib/espMqttClient/src/MqttClient.cpp b/lib/espMqttClient/src/MqttClient.cpp
index bae592ee..fdc2cb2d 100644
--- a/lib/espMqttClient/src/MqttClient.cpp
+++ b/lib/espMqttClient/src/MqttClient.cpp
@@ -14,12 +14,8 @@ using espMqttClientTypes::DisconnectReason;
 using espMqttClientTypes::Error;
 
 MqttClient::MqttClient(espMqttClientTypes::UseInternalTask useInternalTask, uint8_t priority, uint8_t core)
-#if defined(ARDUINO_ARCH_ESP32)
 : _useInternalTask(useInternalTask)
 , _transport(nullptr)
-#else
-: _transport(nullptr)
-#endif
 , _onConnectCallback(nullptr)
 , _onDisconnectCallback(nullptr)
 , _onSubscribeCallback(nullptr)
@@ -41,7 +37,7 @@ MqttClient::MqttClient(espMqttClientTypes::UseInternalTask useInternalTask, uint
 , _willPayloadLength(0)
 , _willQos(0)
 , _willRetain(false)
-, _timeout(10000)
+, _timeout(EMC_TX_TIMEOUT)
 , _state(State::disconnected)
 , _generatedClientId{0}
 , _packetId(0)
@@ -101,7 +97,7 @@ bool MqttClient::disconnected() const {
 }
 
 bool MqttClient::connect() {
-  bool result = true;
+  bool result = false;
   if (_state == State::disconnected) {
     EMC_SEMAPHORE_TAKE();
     if (_addPacketFront(_cleanSession,
@@ -114,17 +110,17 @@ bool MqttClient::connect() {
                         _willPayloadLength,
                         (uint16_t)(_keepAlive / 1000),  // 32b to 16b doesn't overflow because it comes from 16b orignally
                         _clientId)) {
+      result = true;
+      _setState(State::connectingTcp1);
       #if defined(ARDUINO_ARCH_ESP32)
       if (_useInternalTask == espMqttClientTypes::UseInternalTask::YES) {
         vTaskResume(_taskHandle);
       }
       #endif
-      _state = State::connectingTcp1;
     } else {
       EMC_SEMAPHORE_GIVE();
       emc_log_e("Could not create CONNECT packet");
       _onError(0, Error::OUT_OF_MEMORY);
-      result = false;
     }
     EMC_SEMAPHORE_GIVE();
   }
@@ -133,11 +129,11 @@ bool MqttClient::connect() {
 
 bool MqttClient::disconnect(bool force) {
   if (force && _state != State::disconnected && _state != State::disconnectingTcp1 && _state != State::disconnectingTcp2) {
-    _state = State::disconnectingTcp1;
+    _setState(State::disconnectingTcp1);
     return true;
   }
   if (!force && _state == State::connected) {
-    _state = State::disconnectingMqtt1;
+    _setState(State::disconnectingMqtt1);
     return true;
   }
   return false;
@@ -151,8 +147,8 @@ uint16_t MqttClient::publish(const char* topic, uint8_t qos, bool retain, const
   #endif
     return 0;
   }
-  uint16_t packetId = (qos > 0) ? _getNextPacketId() : 1;
   EMC_SEMAPHORE_TAKE();
+  uint16_t packetId = (qos > 0) ? _getNextPacketId() : 1;
   if (!_addPacket(packetId, topic, payload, length, qos, retain)) {
     emc_log_e("Could not create PUBLISH packet");
     _onError(packetId, Error::OUT_OF_MEMORY);
@@ -175,8 +171,8 @@ uint16_t MqttClient::publish(const char* topic, uint8_t qos, bool retain, espMqt
   #endif
     return 0;
   }
-  uint16_t packetId = (qos > 0) ? _getNextPacketId() : 1;
   EMC_SEMAPHORE_TAKE();
+  uint16_t packetId = (qos > 0) ? _getNextPacketId() : 1;
   if (!_addPacket(packetId, topic, callback, length, qos, retain)) {
     emc_log_e("Could not create PUBLISH packet");
     _onError(packetId, Error::OUT_OF_MEMORY);
@@ -194,6 +190,14 @@ const char* MqttClient::getClientId() const {
   return _clientId;
 }
 
+size_t MqttClient::queueSize() {
+  size_t ret = 0;
+  EMC_SEMAPHORE_TAKE();
+  ret = _outbox.size();
+  EMC_SEMAPHORE_GIVE();
+  return ret;
+}
+
 void MqttClient::loop() {
   switch (_state) {
     case State::disconnected:
@@ -205,9 +209,9 @@ void MqttClient::loop() {
       break;
     case State::connectingTcp1:
       if (_useIp ? _transport->connect(_ip, _port) : _transport->connect(_host, _port)) {
-        _state = State::connectingTcp2;
+        _setState(State::connectingTcp2);
       } else {
-        _state = State::disconnectingTcp1;
+        _setState(State::disconnectingTcp1);
         _disconnectReason = DisconnectReason::TCP_DISCONNECTED;
         break;
       }
@@ -217,7 +221,7 @@ void MqttClient::loop() {
       if (_transport->connected()) {
         _parser.reset();
         _lastClientActivity = _lastServerActivity = millis();
-        _state = State::connectingMqtt;
+        _setState(State::connectingMqtt);
       }
       break;
     case State::connectingMqtt:
@@ -227,7 +231,7 @@ void MqttClient::loop() {
         _checkIncoming();
         _checkPing();
       } else {
-        _state = State::disconnectingTcp1;
+        _setState(State::disconnectingTcp1);
         _disconnectReason = DisconnectReason::TCP_DISCONNECTED;
       }
       break;
@@ -247,7 +251,7 @@ void MqttClient::loop() {
         _checkPing();
         _checkTimeout();
       } else {
-        _state = State::disconnectingTcp1;
+        _setState(State::disconnectingTcp1);
         _disconnectReason = DisconnectReason::TCP_DISCONNECTED;
       }
       break;
@@ -259,7 +263,7 @@ void MqttClient::loop() {
           emc_log_e("Could not create DISCONNECT packet");
           _onError(0, Error::OUT_OF_MEMORY);
         } else {
-          _state = State::disconnectingMqtt2;
+          _setState(State::disconnectingMqtt2);
         }
       }
       EMC_SEMAPHORE_GIVE();
@@ -270,13 +274,13 @@ void MqttClient::loop() {
       break;
     case State::disconnectingTcp1:
       _transport->stop();
-      _state = State::disconnectingTcp2;
+      _setState(State::disconnectingTcp2);
       break;  // keep break to accomodate async clients
     case State::disconnectingTcp2:
       if (_transport->disconnected()) {
         _clearQueue(0);
         _bytesSent = 0;
-        _state = State::disconnected;
+        _setState(State::disconnected);
         if (_onDisconnectCallback) _onDisconnectCallback(_disconnectReason);
       }
       break;
@@ -308,13 +312,15 @@ void MqttClient::_loop(MqttClient* c) {
 }
 #endif
 
+inline void MqttClient::_setState(State newState) {
+  emc_log_i("state %i --> %i", static_cast<std::underlying_type<State>::type>(_state.load()), static_cast<std::underlying_type<State>::type>(newState));
+  _state = newState;
+}
+
 uint16_t MqttClient::_getNextPacketId() {
-  uint16_t packetId = 0;
-  EMC_SEMAPHORE_TAKE();
-  // cppcheck-suppress knownConditionTrueFalse
-  packetId = (++_packetId == 0) ? ++_packetId : _packetId;
-  EMC_SEMAPHORE_GIVE();
-  return packetId;
+  ++_packetId;
+  if (_packetId == 0) ++_packetId;
+  return _packetId;
 }
 
 void MqttClient::_checkOutbox() {
@@ -329,21 +335,14 @@ int MqttClient::_sendPacket() {
   EMC_SEMAPHORE_TAKE();
   OutgoingPacket* packet = _outbox.getCurrent();
 
-  int32_t wantToWrite = 0;
-  int32_t written = 0;
-  if (packet && (wantToWrite == written)) {
-    // mixing signed with unsigned here but safe because of MQTT packet size limits
-    wantToWrite = packet->packet.available(_bytesSent);
+  size_t written = 0;
+  if (packet) {
+    size_t wantToWrite = packet->packet.available(_bytesSent);
     if (wantToWrite == 0) {
       EMC_SEMAPHORE_GIVE();
       return 0;
     }
     written = _transport->write(packet->packet.data(_bytesSent), wantToWrite);
-    if (written < 0) {
-      emc_log_w("Write error, check connection");
-      EMC_SEMAPHORE_GIVE();
-      return -1;
-    }
     packet->timeSent = millis();
     _lastClientActivity = millis();
     _bytesSent += written;
@@ -358,7 +357,7 @@ bool MqttClient::_advanceOutbox() {
   OutgoingPacket* packet = _outbox.getCurrent();
   if (packet && _bytesSent == packet->packet.size()) {
     if ((packet->packet.packetType()) == PacketType.DISCONNECT) {
-      _state = State::disconnectingTcp1;
+      _setState(State::disconnectingTcp1);
       _disconnectReason = DisconnectReason::USER_OK;
     }
     if (packet->packet.removable()) {
@@ -388,7 +387,7 @@ void MqttClient::_checkIncoming() {
         espMqttClientInternals::MQTTPacketType packetType = _parser.getPacket().fixedHeader.packetType & 0xF0;
         if (_state == State::connectingMqtt && packetType != PacketType.CONNACK) {
           emc_log_w("Disconnecting, expected CONNACK - protocol error");
-          _state = State::disconnectingTcp1;
+          _setState(State::disconnectingTcp1);
           return;
         }
         switch (packetType & 0xF0) {
@@ -426,7 +425,7 @@ void MqttClient::_checkIncoming() {
         }
       } else if (result ==  espMqttClientInternals::ParserResult::protocolError) {
         emc_log_w("Disconnecting, protocol error");
-        _state = State::disconnectingTcp1;
+        _setState(State::disconnectingTcp1);
         _disconnectReason = DisconnectReason::TCP_DISCONNECTED;
         return;
       }
@@ -446,7 +445,7 @@ void MqttClient::_checkPing() {
   // disconnect when server was inactive for twice the keepalive time
   if (currentMillis - _lastServerActivity > 2 * _keepAlive) {
     emc_log_w("Disconnecting, server exceeded keepalive");
-    _state = State::disconnectingTcp1;
+    _setState(State::disconnectingTcp1);
     _disconnectReason = DisconnectReason::TCP_DISCONNECTED;
     return;
   }
@@ -484,7 +483,7 @@ void MqttClient::_checkTimeout() {
 void MqttClient::_onConnack() {
   if (_parser.getPacket().variableHeader.fixed.connackVarHeader.returnCode == 0x00) {
     _pingSent = false;  // reset after keepalive timeout disconnect
-    _state = State::connected;
+    _setState(State::connected);
     _advanceOutbox();
     if (_parser.getPacket().variableHeader.fixed.connackVarHeader.sessionPresent == 0) {
       _clearQueue(1);
@@ -493,14 +492,14 @@ void MqttClient::_onConnack() {
       _onConnectCallback(_parser.getPacket().variableHeader.fixed.connackVarHeader.sessionPresent);
     }
   } else {
-    _state = State::disconnectingTcp1;
+    _setState(State::disconnectingTcp1);
     // cast is safe because the parser already checked for a valid return code
     _disconnectReason = static_cast<DisconnectReason>(_parser.getPacket().variableHeader.fixed.connackVarHeader.returnCode);
   }
 }
 
 void MqttClient::_onPublish() {
-  espMqttClientInternals::IncomingPacket p = _parser.getPacket();
+  const espMqttClientInternals::IncomingPacket& p = _parser.getPacket();
   uint8_t qos = p.qos();
   bool retain = p.retain();
   bool dup = p.dup();
@@ -633,9 +632,6 @@ void MqttClient::_onPubcomp() {
     // if it doesn't match the ID, return
     if ((it.get()->packet.packetType()) == PacketType.PUBREL) {
       if (it.get()->packet.packetId() == idToMatch) {
-        if (!_addPacket(PacketType.PUBCOMP, idToMatch)) {
-          emc_log_e("Could not create PUBCOMP packet");
-        }
         callback = true;
         _outbox.remove(it);
         break;
diff --git a/lib/espMqttClient/src/MqttClient.h b/lib/espMqttClient/src/MqttClient.h
index 8d89abab..49979427 100644
--- a/lib/espMqttClient/src/MqttClient.h
+++ b/lib/espMqttClient/src/MqttClient.h
@@ -65,6 +65,7 @@ class MqttClient {
   uint16_t publish(const char* topic, uint8_t qos, bool retain, espMqttClientTypes::PayloadCallback callback, size_t length);
   void clearQueue(bool deleteSessionData = false);  // Not MQTT compliant and may cause unpredictable results when `deleteSessionData` = true!
   const char* getClientId() const;
+  size_t queueSize();  // No const because of mutex
   void loop();
 
  protected:
@@ -110,6 +111,7 @@ class MqttClient {
     disconnectingTcp2 =  8
   };
   std::atomic<State> _state;
+  inline void _setState(State newState);
 
  private:
   char _generatedClientId[EMC_CLIENTID_LENGTH];
@@ -130,7 +132,7 @@ class MqttClient {
     uint32_t timeSent;
     espMqttClientInternals::Packet packet;
     template <typename... Args>
-    OutgoingPacket(uint32_t t, espMqttClientTypes::Error error, Args&&... args) :
+    OutgoingPacket(uint32_t t, espMqttClientTypes::Error& error, Args&&... args) :  // NOLINT(runtime/references)
       timeSent(t),
       packet(error, std::forward<Args>(args) ...) {}
   };
@@ -148,16 +150,24 @@ class MqttClient {
   bool _addPacket(Args&&... args) {
     espMqttClientTypes::Error error(espMqttClientTypes::Error::SUCCESS);
     espMqttClientInternals::Outbox<OutgoingPacket>::Iterator it = _outbox.emplace(0, error, std::forward<Args>(args) ...);
-    if (it && error == espMqttClientTypes::Error::SUCCESS) return true;
-    return false;
+    if (it && error == espMqttClientTypes::Error::SUCCESS) {
+      return true;
+    } else {
+      if (it) _outbox.remove(it);
+      return false;
+    }
   }
 
   template <typename... Args>
   bool _addPacketFront(Args&&... args) {
     espMqttClientTypes::Error error(espMqttClientTypes::Error::SUCCESS);
     espMqttClientInternals::Outbox<OutgoingPacket>::Iterator it = _outbox.emplaceFront(0, error, std::forward<Args>(args) ...);
-    if (it && error == espMqttClientTypes::Error::SUCCESS) return true;
-    return false;
+    if (it && error == espMqttClientTypes::Error::SUCCESS) {
+      return true;
+    } else {
+      if (it) _outbox.remove(it);
+      return false;
+    }
   }
 
   void _checkOutbox();
diff --git a/lib/espMqttClient/src/MqttClientSetup.h b/lib/espMqttClient/src/MqttClientSetup.h
index 73458d47..67f46a07 100644
--- a/lib/espMqttClient/src/MqttClientSetup.h
+++ b/lib/espMqttClient/src/MqttClientSetup.h
@@ -11,6 +11,11 @@ the LICENSE file.
 
 #pragma once
 
+#if EMC_MULTIPLE_CALLBACKS
+#include <list>
+#include <utility>
+#endif
+
 #include "MqttClient.h"
 
 template <typename T>
@@ -73,35 +78,127 @@ class MqttClientSetup : public MqttClient {
     return static_cast<T&>(*this);
   }
 
-  T& onConnect(espMqttClientTypes::OnConnectCallback callback) {
+  T& onConnect(espMqttClientTypes::OnConnectCallback callback, uint32_t id = 0) {
+    #if EMC_MULTIPLE_CALLBACKS
+    _onConnectCallbacks.emplace_back(callback, id);
+    #else
+    (void) id;
     _onConnectCallback = callback;
+    #endif
     return static_cast<T&>(*this);
   }
 
-  T& onDisconnect(espMqttClientTypes::OnDisconnectCallback callback) {
+  T& onDisconnect(espMqttClientTypes::OnDisconnectCallback callback, uint32_t id = 0) {
+    #if EMC_MULTIPLE_CALLBACKS
+    _onDisconnectCallbacks.emplace_back(callback, id);
+    #else
+    (void) id;
     _onDisconnectCallback = callback;
+    #endif
     return static_cast<T&>(*this);
   }
 
-  T& onSubscribe(espMqttClientTypes::OnSubscribeCallback callback) {
+  T& onSubscribe(espMqttClientTypes::OnSubscribeCallback callback, uint32_t id = 0) {
+    #if EMC_MULTIPLE_CALLBACKS
+    _onSubscribeCallbacks.emplace_back(callback, id);
+    #else
+    (void) id;
     _onSubscribeCallback = callback;
+    #endif
     return static_cast<T&>(*this);
   }
 
-  T& onUnsubscribe(espMqttClientTypes::OnUnsubscribeCallback callback) {
+  T& onUnsubscribe(espMqttClientTypes::OnUnsubscribeCallback callback, uint32_t id = 0) {
+    #if EMC_MULTIPLE_CALLBACKS
+    _onUnsubscribeCallbacks.emplace_back(callback, id);
+    #else
+    (void) id;
     _onUnsubscribeCallback = callback;
+    #endif
     return static_cast<T&>(*this);
   }
 
-  T& onMessage(espMqttClientTypes::OnMessageCallback callback) {
+  T& onMessage(espMqttClientTypes::OnMessageCallback callback, uint32_t id = 0) {
+    #if EMC_MULTIPLE_CALLBACKS
+    _onMessageCallbacks.emplace_back(callback, id);
+    #else
+    (void) id;
     _onMessageCallback = callback;
+    #endif
     return static_cast<T&>(*this);
   }
 
-  T& onPublish(espMqttClientTypes::OnPublishCallback callback) {
+  T& onPublish(espMqttClientTypes::OnPublishCallback callback, uint32_t id = 0) {
+    #if EMC_MULTIPLE_CALLBACKS
+    _onPublishCallbacks.emplace_back(callback, id);
+    #else
+    (void) id;
     _onPublishCallback = callback;
+    #endif
+    return static_cast<T&>(*this);
+  }
+
+  #if EMC_MULTIPLE_CALLBACKS
+  T& removeOnConnect(uint32_t id) {
+    for (auto it = _onConnectCallbacks.begin(); it != _onConnectCallbacks.end(); ++it) {
+      if (it->second == id) {
+        _onConnectCallbacks.erase(it);
+        break;
+      }
+    }
+    return static_cast<T&>(*this);
+  }
+
+  T& removeOnDisconnect(uint32_t id) {
+    for (auto it = _onDisconnectCallbacks.begin(); it != _onDisconnectCallbacks.end(); ++it) {
+      if (it->second == id) {
+        _onDisconnectCallbacks.erase(it);
+        break;
+      }
+    }
+    return static_cast<T&>(*this);
+  }
+
+  T& removeOnSubscribe(uint32_t id) {
+    for (auto it = _onSubscribeCallbacks.begin(); it != _onSubscribeCallbacks.end(); ++it) {
+      if (it->second == id) {
+        _onSubscribeCallbacks.erase(it);
+        break;
+      }
+    }
+    return static_cast<T&>(*this);
+  }
+
+  T& removeOnUnsubscribe(uint32_t id) {
+    for (auto it = _onUnsubscribeCallbacks.begin(); it != _onUnsubscribeCallbacks.end(); ++it) {
+      if (it->second == id) {
+        _onUnsubscribeCallbacks.erase(it);
+        break;
+      }
+    }
+    return static_cast<T&>(*this);
+  }
+
+  T& removeOnMessage(uint32_t id) {
+    for (auto it = _onMessageCallbacks.begin(); it != _onMessageCallbacks.end(); ++it) {
+      if (it->second == id) {
+        _onMessageCallbacks.erase(it);
+        break;
+      }
+    }
+    return static_cast<T&>(*this);
+  }
+
+  T& removeOnPublish(uint32_t id) {
+    for (auto it = _onPublishCallbacks.begin(); it != _onPublishCallbacks.end(); ++it) {
+      if (it->second == id) {
+        _onPublishCallbacks.erase(it);
+        break;
+      }
+    }
     return static_cast<T&>(*this);
   }
+  #endif
 
   /*
   T& onError(espMqttClientTypes::OnErrorCallback callback) {
@@ -112,5 +209,37 @@ class MqttClientSetup : public MqttClient {
 
  protected:
   explicit MqttClientSetup(espMqttClientTypes::UseInternalTask useInternalTask, uint8_t priority = 1, uint8_t core = 1)
-  : MqttClient(useInternalTask, priority, core) {}
+  : MqttClient(useInternalTask, priority, core) {
+    #if EMC_MULTIPLE_CALLBACKS
+    _onConnectCallback = [this](bool sessionPresent) {
+      for (auto callback : _onConnectCallbacks) if (callback.first) callback.first(sessionPresent);
+    };
+    _onDisconnectCallback = [this](espMqttClientTypes::DisconnectReason reason) {
+      for (auto callback : _onDisconnectCallbacks) if (callback.first) callback.first(reason);
+    };
+    _onSubscribeCallback = [this](uint16_t packetId, const espMqttClientTypes::SubscribeReturncode* returncodes, size_t len) {
+      for (auto callback : _onSubscribeCallbacks) if (callback.first) callback.first(packetId, returncodes, len);
+    };
+    _onUnsubscribeCallback = [this](int16_t packetId) {
+      for (auto callback : _onUnsubscribeCallbacks) if (callback.first) callback.first(packetId);
+    };
+    _onMessageCallback = [this](const espMqttClientTypes::MessageProperties& properties, const char* topic, const uint8_t* payload, size_t len, size_t index, size_t total) {
+      for (auto callback : _onMessageCallbacks) if (callback.first) callback.first(properties, topic, payload, len, index, total);
+    };
+    _onPublishCallback = [this](uint16_t packetId) {
+      for (auto callback : _onPublishCallbacks) if (callback.first) callback.first(packetId);
+    };
+    #else
+    // empty
+    #endif
+  }
+
+  #if EMC_MULTIPLE_CALLBACKS
+  std::list<std::pair<espMqttClientTypes::OnConnectCallback, uint32_t>> _onConnectCallbacks;
+  std::list<std::pair<espMqttClientTypes::OnDisconnectCallback, uint32_t>> _onDisconnectCallbacks;
+  std::list<std::pair<espMqttClientTypes::OnSubscribeCallback, uint32_t>> _onSubscribeCallbacks;
+  std::list<std::pair<espMqttClientTypes::OnUnsubscribeCallback, uint32_t>> _onUnsubscribeCallbacks;
+  std::list<std::pair<espMqttClientTypes::OnMessageCallback, uint32_t>> _onMessageCallbacks;
+  std::list<std::pair<espMqttClientTypes::OnPublishCallback, uint32_t>> _onPublishCallbacks;
+  #endif
 };
diff --git a/lib/espMqttClient/src/Outbox.h b/lib/espMqttClient/src/Outbox.h
index b123b389..486b6acf 100644
--- a/lib/espMqttClient/src/Outbox.h
+++ b/lib/espMqttClient/src/Outbox.h
@@ -163,6 +163,16 @@ class Outbox {
     return false;
   }
 
+  size_t size() const {
+    Node* n = _first;
+    size_t count = 0;
+    while (n) {
+      n = n->next;
+      ++count;
+    }
+    return count;
+  }
+
  private:
   Node* _first;
   Node* _last;
diff --git a/lib/espMqttClient/src/Packets/Packet.cpp b/lib/espMqttClient/src/Packets/Packet.cpp
index df463ef7..2f84b503 100644
--- a/lib/espMqttClient/src/Packets/Packet.cpp
+++ b/lib/espMqttClient/src/Packets/Packet.cpp
@@ -100,7 +100,7 @@ Packet::Packet(espMqttClientTypes::Error& error,
   (password ? 2 + strlen(password) : 0);
 
   // allocate memory
-  if (!_allocate(remainingLength)) {
+  if (!_allocate(remainingLength, false)) {
     error = espMqttClientTypes::Error::OUT_OF_MEMORY;
     return;
   }
@@ -300,8 +300,8 @@ Packet::Packet(espMqttClientTypes::Error& error, MQTTPacketType type)
 }
 
 
-bool Packet::_allocate(size_t remainingLength) {
-  if (EMC_GET_FREE_MEMORY() < EMC_MIN_FREE_MEMORY) {
+bool Packet::_allocate(size_t remainingLength, bool check) {
+  if (check && EMC_GET_FREE_MEMORY() < EMC_MIN_FREE_MEMORY) {
     emc_log_w("Packet buffer not allocated: low memory");
     return false;
   }
diff --git a/lib/espMqttClient/src/Packets/Packet.h b/lib/espMqttClient/src/Packets/Packet.h
index 21d5e0a9..00019fb1 100644
--- a/lib/espMqttClient/src/Packets/Packet.h
+++ b/lib/espMqttClient/src/Packets/Packet.h
@@ -12,12 +12,12 @@ the LICENSE file.
 #include <stddef.h>
 
 #include "Constants.h"
-#include "Config.h"
+#include "../Config.h"
 #include "../TypeDefs.h"
 #include "../Helpers.h"
 #include "../Logging.h"
 #include "RemainingLength.h"
-#include "String.h"
+#include "StringUtil.h"
 
 namespace espMqttClientInternals {
 
@@ -97,7 +97,7 @@ class Packet {
   , _payloadStartIndex(0)
   , _payloadEndIndex(0)
   , _getPayload(nullptr) {
-    static_assert(sizeof...(Args) % 2 == 0);
+    static_assert(sizeof...(Args) % 2 == 0, "Subscribe should be in topic/qos pairs");
     size_t numberTopics = 2 + (sizeof...(Args) / 2);
     SubscribeItem list[numberTopics] = {topic1, qos1, topic2, qos2, args...};
     _createSubscribe(error, list, numberTopics);
@@ -133,7 +133,7 @@ class Packet {
 
  private:
   // pass remainingLength = total size - header - remainingLengthLength!
-  bool _allocate(size_t remainingLength);
+  bool _allocate(size_t remainingLength, bool check = true);
 
   // fills header and returns index of next available byte in buffer
   size_t _fillPublishHeader(uint16_t packetId,
diff --git a/lib/espMqttClient/src/Packets/String.cpp b/lib/espMqttClient/src/Packets/StringUtil.cpp
similarity index 96%
rename from lib/espMqttClient/src/Packets/String.cpp
rename to lib/espMqttClient/src/Packets/StringUtil.cpp
index c3fe23fd..7cd3dd8c 100644
--- a/lib/espMqttClient/src/Packets/String.cpp
+++ b/lib/espMqttClient/src/Packets/StringUtil.cpp
@@ -6,7 +6,7 @@ For a copy, see <https://opensource.org/licenses/MIT> or
 the LICENSE file.
 */
 
-#include "String.h"
+#include "StringUtil.h"
 
 namespace espMqttClientInternals {
 
diff --git a/lib/espMqttClient/src/Packets/String.h b/lib/espMqttClient/src/Packets/StringUtil.h
similarity index 100%
rename from lib/espMqttClient/src/Packets/String.h
rename to lib/espMqttClient/src/Packets/StringUtil.h
diff --git a/lib/espMqttClient/src/Transport/ClientPosix.cpp b/lib/espMqttClient/src/Transport/ClientPosix.cpp
index 83b555d1..1cd66e2b 100644
--- a/lib/espMqttClient/src/Transport/ClientPosix.cpp
+++ b/lib/espMqttClient/src/Transport/ClientPosix.cpp
@@ -40,7 +40,7 @@ bool ClientPosix::connect(IPAddress ip, uint16_t port) {
   _host.sin_addr.s_addr = htonl(uint32_t(ip));
   _host.sin_port = ::htons(port);
 
-  int ret = ::connect(_sockfd, (struct sockaddr *)&_host, sizeof(_host));
+  int ret = ::connect(_sockfd, reinterpret_cast<sockaddr*>(&_host), sizeof(_host));
 
   if (ret < 0) {
     emc_log_e("Error connecting: %d - (%d) %s", ret, errno, strerror(errno));
diff --git a/lib/espMqttClient/src/Transport/ClientPosix.h b/lib/espMqttClient/src/Transport/ClientPosix.h
index a2f9c9fa..af0dd4bf 100644
--- a/lib/espMqttClient/src/Transport/ClientPosix.h
+++ b/lib/espMqttClient/src/Transport/ClientPosix.h
@@ -43,7 +43,7 @@ class ClientPosix : public Transport {
 
  protected:
   int _sockfd;
-  struct sockaddr_in _host;
+  sockaddr_in _host;
 };
 
 }  // namespace espMqttClientInternals
diff --git a/lib/espMqttClient/src/Transport/IPAddress.cpp b/lib/espMqttClient/src/Transport/ClientPosixIPAddress.cpp
similarity index 94%
rename from lib/espMqttClient/src/Transport/IPAddress.cpp
rename to lib/espMqttClient/src/Transport/ClientPosixIPAddress.cpp
index b198429d..3386dec8 100644
--- a/lib/espMqttClient/src/Transport/IPAddress.cpp
+++ b/lib/espMqttClient/src/Transport/ClientPosixIPAddress.cpp
@@ -8,7 +8,7 @@ the LICENSE file.
 
 #if defined(__linux__)
 
-#include "IPAddress.h"
+#include "ClientPosixIPAddress.h"
 
 IPAddress::IPAddress()
 : _address(0) {
diff --git a/lib/espMqttClient/src/Transport/IPAddress.h b/lib/espMqttClient/src/Transport/ClientPosixIPAddress.h
similarity index 100%
rename from lib/espMqttClient/src/Transport/IPAddress.h
rename to lib/espMqttClient/src/Transport/ClientPosixIPAddress.h
diff --git a/lib/espMqttClient/src/Transport/Transport.h b/lib/espMqttClient/src/Transport/Transport.h
index 6720c024..d368d018 100644
--- a/lib/espMqttClient/src/Transport/Transport.h
+++ b/lib/espMqttClient/src/Transport/Transport.h
@@ -10,7 +10,7 @@ the LICENSE file.
 
 #include <stddef.h>  // size_t
 
-#include "IPAddress.h"
+#include "ClientPosixIPAddress.h"
 
 namespace espMqttClientInternals {
 
diff --git a/lib/espMqttClient/test/test_client_native/test_client_native.cpp b/lib/espMqttClient/test/test_client_native/test_client_native.cpp
index 7afd7e12..db70a542 100644
--- a/lib/espMqttClient/test/test_client_native/test_client_native.cpp
+++ b/lib/espMqttClient/test/test_client_native/test_client_native.cpp
@@ -7,6 +7,12 @@ void setUp() {}
 void tearDown() {}
 
 espMqttClient mqttClient;
+uint32_t onConnectCbId = 1;
+uint32_t onDisconnectCbId = 2;
+uint32_t onSubscribeCbId = 3;
+uint32_t onUnsubscribeCbId = 4;
+uint32_t onMessageCbId = 5;
+uint32_t onPublishCbId = 6;
 std::atomic_bool exitProgram(false);
 std::thread t;
 
@@ -30,7 +36,7 @@ void test_connect() {
             .onConnect([&](bool sessionPresent) mutable {
               sessionPresentTest = sessionPresent;
               onConnectCalledTest = true;
-            });
+            }, onConnectCbId);
   mqttClient.connect();
   uint32_t start = millis();
   while (millis() - start < 2000) {
@@ -44,7 +50,7 @@ void test_connect() {
   TEST_ASSERT_TRUE(onConnectCalledTest);
   TEST_ASSERT_FALSE(sessionPresentTest);
 
-  mqttClient.onConnect(nullptr);
+  mqttClient.removeOnConnect(onConnectCbId);
 }
 
 /*
@@ -83,7 +89,7 @@ void test_subscribe() {
     if (len == 1 && returncodes[0] == espMqttClientTypes::SubscribeReturncode::QOS0) {
       subscribeTest = true;
     }
-  });
+  }, onSubscribeCbId);
   mqttClient.subscribe("test/test", 0);
   uint32_t start = millis();
   while (millis() - start < 2000) {
@@ -96,7 +102,7 @@ void test_subscribe() {
   TEST_ASSERT_TRUE(mqttClient.connected());
   TEST_ASSERT_TRUE(subscribeTest);
 
-  mqttClient.onSubscribe(nullptr);
+  mqttClient.removeOnSubscribe(onSubscribeCbId);
 }
 
 /*
@@ -112,7 +118,7 @@ void test_publish() {
   mqttClient.onPublish([&](uint16_t packetId) mutable {
     (void) packetId;
     publishSendTest++;
-  });
+  }, onPublishCbId);
   std::atomic<int> publishReceiveTest(0);
   mqttClient.onMessage([&](const espMqttClientTypes::MessageProperties& properties, const char* topic, const uint8_t* payload, size_t len, size_t index, size_t total) mutable {
     (void) properties;
@@ -122,7 +128,7 @@ void test_publish() {
     (void) index;
     (void) total;
     publishReceiveTest++;
-  });
+  }, onMessageCbId);
   uint16_t sendQos0Test = mqttClient.publish("test/test", 0, false, "test0");
   uint16_t sendQos1Test = mqttClient.publish("test/test", 1, false, "test1");
   uint16_t sendQos2Test = mqttClient.publish("test/test", 2, false, "test2");
@@ -138,8 +144,8 @@ void test_publish() {
   TEST_ASSERT_EQUAL_INT(2, publishSendTest);
   TEST_ASSERT_EQUAL_INT(3, publishReceiveTest);
 
-  mqttClient.onPublish(nullptr);
-  mqttClient.onMessage(nullptr);
+  mqttClient.removeOnPublish(onPublishCbId);
+  mqttClient.removeOnMessage(onMessageCbId);
 }
 
 void test_publish_empty() {
@@ -147,7 +153,7 @@ void test_publish_empty() {
   mqttClient.onPublish([&](uint16_t packetId) mutable {
     (void) packetId;
     publishSendEmptyTest++;
-  });
+  }, onPublishCbId);
   std::atomic<int> publishReceiveEmptyTest(0);
   mqttClient.onMessage([&](const espMqttClientTypes::MessageProperties& properties, const char* topic, const uint8_t* payload, size_t len, size_t index, size_t total) mutable {
     (void) properties;
@@ -157,7 +163,7 @@ void test_publish_empty() {
     (void) index;
     (void) total;
     publishReceiveEmptyTest++;
-  });
+  }, onMessageCbId);
   uint16_t sendQos0Test = mqttClient.publish("test/test", 0, false, nullptr, 0);
   uint16_t sendQos1Test = mqttClient.publish("test/test", 1, false, nullptr, 0);
   uint16_t sendQos2Test = mqttClient.publish("test/test", 2, false, nullptr, 0);
@@ -173,8 +179,8 @@ void test_publish_empty() {
   TEST_ASSERT_EQUAL_INT(2, publishSendEmptyTest);
   TEST_ASSERT_EQUAL_INT(3, publishReceiveEmptyTest);
 
-  mqttClient.onPublish(nullptr);
-  mqttClient.onMessage(nullptr);
+  mqttClient.removeOnPublish(onPublishCbId);
+  mqttClient.removeOnMessage(onMessageCbId);
 }
 
 /*
@@ -195,13 +201,13 @@ void test_receive1() {
     (void) index;
     (void) total;
     publishReceive1Test++;
-  });
+  }, onMessageCbId);
   mqttClient.onSubscribe([&](uint16_t packetId, const espMqttClientTypes::SubscribeReturncode* returncodes, size_t len) mutable {
     (void) packetId;
     if (len == 1 && returncodes[0] == espMqttClientTypes::SubscribeReturncode::QOS1) {
       mqttClient.publish("test/test", 1, false, "");
     }
-  });
+  }, onSubscribeCbId);
   mqttClient.subscribe("test/test", 1);
   uint32_t start = millis();
   while (millis() - start < 6000) {
@@ -211,8 +217,8 @@ void test_receive1() {
   TEST_ASSERT_TRUE(mqttClient.connected());
   TEST_ASSERT_GREATER_THAN_INT(0, publishReceive1Test);
 
-  mqttClient.onMessage(nullptr);
-  mqttClient.onSubscribe(nullptr);
+  mqttClient.removeOnMessage(onMessageCbId);
+  mqttClient.removeOnSubscribe(onSubscribeCbId);
 }
 
 /*
@@ -233,13 +239,13 @@ void test_receive2() {
     (void) index;
     (void) total;
     publishReceive2Test++;
-  });
+  }, onMessageCbId);
   mqttClient.onSubscribe([&](uint16_t packetId, const espMqttClientTypes::SubscribeReturncode* returncodes, size_t len) mutable {
     (void) packetId;
     if (len == 1 && returncodes[0] == espMqttClientTypes::SubscribeReturncode::QOS2) {
       mqttClient.publish("test/test", 2, false, "");
     }
-  });
+  }, onSubscribeCbId);
   mqttClient.subscribe("test/test", 2);
   uint32_t start = millis();
   while (millis() - start < 6000) {
@@ -249,8 +255,8 @@ void test_receive2() {
   TEST_ASSERT_TRUE(mqttClient.connected());
   TEST_ASSERT_EQUAL_INT(1, publishReceive2Test);
 
-  mqttClient.onMessage(nullptr);
-  mqttClient.onSubscribe(nullptr);
+  mqttClient.removeOnMessage(onMessageCbId);
+  mqttClient.removeOnSubscribe(onSubscribeCbId);
 }
 
 
@@ -265,7 +271,7 @@ void test_unsubscribe() {
   mqttClient.onUnsubscribe([&](uint16_t packetId) mutable {
     (void) packetId;
     unsubscribeTest = true;
-  });
+  }, onUnsubscribeCbId);
   mqttClient.unsubscribe("test/test");
   uint32_t start = millis();
   while (millis() - start < 2000) {
@@ -278,7 +284,7 @@ void test_unsubscribe() {
   TEST_ASSERT_TRUE(mqttClient.connected());
   TEST_ASSERT_TRUE(unsubscribeTest);
 
-  mqttClient.onUnsubscribe(nullptr);
+  mqttClient.removeOnUnsubscribe(onUnsubscribeCbId);
 }
 
 /*
@@ -293,7 +299,7 @@ void test_disconnect() {
   mqttClient.onDisconnect([&](espMqttClientTypes::DisconnectReason reason) mutable {
     reasonTest = reason;
     onDisconnectCalled = true;
-  });
+  }, onDisconnectCbId);
   mqttClient.disconnect();
   uint32_t start = millis();
   while (millis() - start < 2000) {
@@ -307,7 +313,7 @@ void test_disconnect() {
   TEST_ASSERT_EQUAL_UINT8(espMqttClientTypes::DisconnectReason::USER_OK, reasonTest);
   TEST_ASSERT_TRUE(mqttClient.disconnected());
 
-  mqttClient.onDisconnect(nullptr);
+  mqttClient.removeOnDisconnect(onDisconnectCbId);
 }
 
 void test_pub_before_connect() {
@@ -320,11 +326,11 @@ void test_pub_before_connect() {
             .onConnect([&](bool sessionPresent) mutable {
               sessionPresentTest = sessionPresent;
               onConnectCalledTest = true;
-            })
+            }, onConnectCbId)
             .onPublish([&](uint16_t packetId) mutable {
               (void) packetId;
               publishSendTest++;
-            });
+            }, onPublishCbId);
   uint16_t sendQos0Test = mqttClient.publish("test/test", 0, false, "test0");
   uint16_t sendQos1Test = mqttClient.publish("test/test", 1, false, "test1");
   uint16_t sendQos2Test = mqttClient.publish("test/test", 2, false, "test2");
@@ -349,8 +355,8 @@ void test_pub_before_connect() {
   TEST_ASSERT_GREATER_THAN_UINT16(0, sendQos2Test);
   TEST_ASSERT_EQUAL_INT(2, publishSendTest);
 
-  mqttClient.onConnect(nullptr);
-  mqttClient.onPublish(nullptr);
+  mqttClient.removeOnConnect(onConnectCbId);
+  mqttClient.removeOnPublish(onPublishCbId);
 }
 
 void final_disconnect() {
@@ -358,7 +364,7 @@ void final_disconnect() {
   mqttClient.onDisconnect([&](espMqttClientTypes::DisconnectReason reason) mutable {
     (void) reason;
     onDisconnectCalled = true;
-  });
+  }, onDisconnectCbId);
   mqttClient.disconnect();
   uint32_t start = millis();
   while (millis() - start < 2000) {
@@ -370,7 +376,7 @@ void final_disconnect() {
   if (mqttClient.connected()) {
     mqttClient.disconnect(true);
   }
-  mqttClient.onDisconnect(nullptr);
+  mqttClient.removeOnDisconnect(onDisconnectCbId);
 }
 
 int main() {
diff --git a/lib/espMqttClient/test/test_string/test_string.cpp b/lib/espMqttClient/test/test_string/test_string.cpp
index a1d67e5d..f171d775 100644
--- a/lib/espMqttClient/test/test_string/test_string.cpp
+++ b/lib/espMqttClient/test/test_string/test_string.cpp
@@ -2,7 +2,7 @@
 
 #include <unity.h>
 
-#include <Packets/String.h>
+#include <Packets/StringUtil.h>
 
 void setUp() {}
 void tearDown() {}