Hello all, I would like to share my solution to a WiFi issue that just occured.
Symptoms: my 2x Shelly Button 1 worked as normal for 1 year now but suddenly wouldn't connect to my Asus WiFi router (in the Clients list it shows up for a few seconds but then disconnects).
Factory reset and firmware upgrade did not help.
Solution: I switched 2.4 GHz Channel from Auto to 6. It seems my Asus router decided to switch to another channel that doesn't work well with my Shelly Button 1s.
For now, it seems that everything is fine again.