TG0WDT_SYS_RESET - Possible WiFi issue?

[greycon]

We have a pilot project, 50 devices deployed around the country, monitoring fridge temperatures. They post temperature data back to our server using a REST API call, every 5 minutes. They are setup on-site to use WiFi. Also, each device is programmed to restart each night, and whenever they restart they check for firmware updates, and also they post back the reason for restart.

Everything has been going very well for 2 weeks, but today I have observed a strange issue. 2 devices on one particular site rebooted in the afternoon, with a reason of Rsx 0x07, which is, I believe TG0WDT_SYS_RESET.

Looking at my readings logs, I can see that there were no readings from any of the 4 devices on that site between 14:17 and 15:47. 2 devices then resumed as normal, but 2 devices seemed to have rebooted after TG0WDT_SYS_RESET.

I'm really looking for ideas here. My current thoughts are that the local WiFi went off for that period, or at least part of it, and whatever stage the offending 2 devices were at, the code hung, and eventually the watchdog timer stepped in. What do you think?

I don't know exactly what TG0WDT_SYS_RESET is, I haven't delved into the IDF source yet, but I'm hoping someone here might be able to give me some pointers.

Thanks.

[greycon]

Further information on this. We have seen, on this site, some resets during the day due to power on, or brownout. I had put this down to it being a factory site, and maybe noisy power lines. Or perhaps sub-standard PSUs.

It would seem, looking at the post below that a Brownout Reset can sometimes be mis-reported as a Watchdog reset:

https://github.com/espressif/esp-idf/issues/10834