WiFi slow/crashy with CircuitPython >= 10.1 on Feather ESP32-C6

[JonNelson]

CircuitPython version and board name

Adafruit CircuitPython 10.1.4 on 2026-03-09; Adafruit Feather ESP32-C6 4MB Flash No PSRAM with ESP32C6

Code/REPL

# No code changes

Behavior

Not a code issue

Description

I have several (4) Adafruit Feather ESP32-C6 and all of them exhibit the same behavior: the WiFi is unusable and very flaky with all versions of CircuitPython >= 10.1.

I have tried 10.0.1 (good), 10.0.3 (great), 10.1.1 through 10.1.4 (all are bad), and 10.2.0-alpha.1.

The symptoms are always the same: extremely slow or crashy (or both) WiFi.

An example crash:

Adafruit CircuitPython 10.1.4 on 2026-03-09; Adafruit Feather ESP32-C6 4MB Flash No PSRAM with ESP32C6
>>> 
>>> ESP-ROM:esp32c6-20220919
Build:Sep 19 2022
rst:0xc (SW_CPU),boot:0x8 (SPI_FAST_FLASH_BOOT)
Saved PC:0x4001975a
SPIWP:0xee
mode:DIO, clock div:2
load:0x40875730,len:0x130
load:0x4086b910,len:0xd40
load:0x4086e610,len:0x2568
entry 0x4086b910

This occurs in response to an HTTP call to the /cp/version.json endpoint (via circup, confirmed via strace).
If I use 10.0.3, however, it's not only crash-free it's also fast.

No code changes at all, only set up WiFi via CIRCUITPY_WIFI_SSID, CIRCUITPY_WIFI_PASSWORD, and CIRCUITPY_WEB_API_PASSWORD in settings.toml

Additional information

No response

[tannewt]

This is likely due to IDF changes. 10.0.x is on f50ec8e(5.4.1) 10.1.x is on f4fddd2(5.5.1) and main is 1d2c73f(5.5.3). It may have been the libc changes going from 5.4 to 5.5 that are causing the issue. I'm not sure exactly.

The next step would be to load a DEBUG=1 build to see if you can get a backtrace during the crash.

[ohararp]

FWIW, I have been seeing similar issues with a FeatherS3. 10.0.3 code running great and subsequent 10.1.3 and .4 upgrades make for a super slow startup and inability to connect to wifi.

[JonNelson]

...

The next step would be to load a DEBUG=1 build to see if you can get a backtrace during the crash.

Are you able to provide some pointers here? I'd prefer to avoid having to build micropython if that's possible.