Use pubsubclient via WireGuard

[proasnet]

Dear @ciniml ,
In my project, I am trying connect ESP32 to HA with wireguard.
VPN tunnel working fine. In WG addon, I see handshake, I can connect via WG with MQTT explorer.

In ESP32 I use example of pubsub client and I get return code from pubsubclient -2 ( the network connection failed )

#include <WiFi.h>
#include "PubSubClient.h"
#include <WireGuard-ESP32.h>


#define ELMAX_DNS "haiot.xxxxxxxx.sk" // secured
// WireGuard configuration --- UPDATE this configuration from JSON
char private_key[] = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";  // [Interface] PrivateKey
IPAddress local_ip( 10 , 10 , 10 , 10 );            // [Interface] Address
char public_key[] = "yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy";     // [Peer] PublicKey
char endpoint_address[] = ELMAX_DNS;    // [Peer] Endpoint
int endpoint_port = 51820;              // [Peer] Endpoint

static WireGuard wg;


const char* ssid = "proasnet";
const char* password = "zzzzzzzz";

int port = 1883;


void callback(char* topic, byte* payload, unsigned int length) {
  // handle message arrived
}

WiFiClient espClient;
PubSubClient client( ELMAX_DNS , 1883 , callback , espClient );


void setup() {
  Serial.begin(115200);

  delay(10);
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  wifiConnect();

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
  Serial.println(WiFi.macAddress());


  Serial.println("Adjusting system time...");
  configTime(9 * 60 * 60, 0, "216.239.35.8");


  wg.begin( local_ip , private_key , endpoint_address , public_key , endpoint_port );

  Serial.println( "setup done..." );
}

void wifiConnect() {
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password, 6);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.print(".");
  }
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();
}


void reconnect() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if ( client.connect("arduinoClient", "espcom", "EsPcom32*85" )) {
      Serial.println("connected");
      // Once connected, publish an announcement...
      client.publish("outTopic", "hello world");
      // ... and resubscribe
      client.subscribe("inTopic");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

The log from WG in HA

peer: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  endpoint: XXX.XXX.XXX.XXX:51820
  allowed ips: 10.10.10.10/32
  latest handshake: 16 seconds ago
  transfer: 601.39 KiB received, 21.87 MiB sent
  persistent keepalive: every 25 seconds