delays with back-to-back TCP connections on ESP32 V2 with 10.1.3

[vladak]

CircuitPython version and board name

Running ESP32V2 with:

configsip: 271414342, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0040,len:436
load:0x40078000,len:14136
load:0x40080400,len:3116
entry 0x40080554
Serial console setup
Adafruit CircuitPython 10.1.3 on 2026-02-20; Adafruit Feather ESP32 V2 with ESP32
Board ID:adafruit_feather_esp32_v2
UID:8EF9D6023F46

Code/REPL

print("Hello world")

Behavior

After configuring the Wi-Fi credentials in settings.toml and resetting, the microcontroller responds to ICMP ECHO request messages and I can connect to TCP port 80 just once. After that it no longer responds to the TCP SYN segments.

supervisor.reload() does not help, the microcontroller has to be reset using microcontroller.reset() only to return to the unhappy state of you-have-one-TCP-connection-for-everything.

While refusing TCP connections on port 80, it is still responding to ping.

Description

No response

Additional information

Reminds me of #7636

[vladak]

Actually, the behavior is more complex: it recovers after couple of seconds so back to back TCP connections are possible, however there is non-negligible delay between next connection can be made.

[vladak]

Looking at the latencies/packet loss of the ICMP messages in my environment, this could be caused by this, hence closing.