ESP32 reverts back to wi-fi provisioning mode after loss of wi-fi connection

[skymuster]

The ESP32 appears to go back into wi-fi provisioning mode (pink LED) after losing wi-fi connectivity, rather retaining the configured credentials and simply reconnecting when wi-fi comes back online. This means that manual intervention is required to re-enter the credentials every time the wi-fi connection goes down, which is not a resilient solution, especially in scenarios where there are scheduled router reboots.

Note: the MQTT config seems to be retained so after re-entering the wi-fi credentials everrything comes back online again.

[lawther]

I had this happen to me as well when I placed the device somewhere out of wifi range.

The behaviour is by design:

#define WIFI_MAX_RETRY_ATTEMPTS        5               // Max connection attempts before clearing credentials
#define WIFI_RETRY_DELAY_MS            5000            // Delay between retry attempts

That will take ~25 seconds to give up, and then

                    // Re-connection failed after being previously connected - clear and restart
                    ESP_LOGE(TAG, "WiFi re-connection failed after %d attempts - clearing credentials and restarting",
                             WIFI_MAX_RETRY_ATTEMPTS);
                    wifi_config_t empty_cfg = {0};
                    esp_wifi_set_config(WIFI_IF_STA, &empty_cfg);
                    vTaskDelay(pdMS_TO_TICKS(WIFI_RESTART_DELAY_MS));
                    esp_restart();

It does seem aggressive.

It looks like ESP32 can run its local AP at the same time as attempting to reconnect to the provisioned network, so that seems like best of both worlds. Eventual recovery from a network outage, but also able to put in new credentials over the local AP if needed. I'd suggest exponential backoff until ~60secs, and then retrying while turning on the local AP.

[zagnuts]

Interesting. Fortunately I haven't struck this yet, but I'm that sod who saturates the local neighbourhood with their WiFi so there is that. With my esphome devices I generally have them set to fire up their local AP if it can't connect to the local WiFi then after 15 mins reboots, but doesn't wipe the credentials, so they retry. So if, for example, the power goes out and then when it comes back on the esphome devices boot up before the local network is up, then they go into AP mode for 15 mins before rebooting and then reconnect.

Rather than having both the device AP active concurrently with trying to connect to the wifi (using up device memory and RF bandwidth), if it's too hard to toggle that AP on/off I'd suggest having a flag that is checked on boot to see if it's doing a failsafe reboot - if it starts up and that flag is set then it goes to AP mode. After (say) 15 mins it then clears the flag and reboots, and attempts to log back onto the local wifi using the saved credentials. If it fails again after 5 tries then it sets that flag and reboots, goes into AP mode and repeat. Just a thought. :-)

[marklynch]

I like the idea of the reboot after 15 minutes of nothing accessing the local AP - and retaining the credentials once it has been configured once. Happy to have a look at that - but in the short term I've increased the retry to 15 seconds and try 10 times - so should be 150 seconds which hopefully solves it for now.

This is done in https://github.com/marklynch/pool-controller-code/releases/tag/v1.5.1