I’ve had a few Sonoff ESP8266 devices go unstable over the last couple of years. No apparent reason just hangs and reboots. Think I’ve got to the bottom of it at least for a few of the devices.
I run Tasmota on them as an OS as its works with my MQTT home automation system really well
It appears that the Flash chips Sonoff use in some of the units are not of the highest quality shall we say.
I had one TH16 unit that wasn’t playing ball. Looked fine but I just couldn’t get it stable so suspecting the Flash, I changed it out for a 4mbit Winbond IC using hot air and some flux.
What a difference!? the unit is lightning fast compared to the others and had been rock solid for a week now.
I would recommend making the change on any Sonoff / ESP8266 unit that’s being random.