Hi, same issue here. There are 2 plug s in the house. One controls the warmwater pump (5w) upstairs and has a schedule every 30 min sometimes every hour to run 400s, then turns off. The other one turns off a device over night via schedule in a room below.
The warmwater plug s randomly gets non responsive. The state is off and one cannot turn it on via button on the plug s. No connection to router any more. The red light is on in a very dimm way. It comes back to live only after plugging it out and in or switching the main fuse switch.. Some times it runs fine for days, weeks and sometimes only 1 day. There is a fritz repeater 2m away. The other plug is also connected to this repeater, as well as 4 other shelly 2.5. All devices have a fixed IP. Repeater uses mesh and is connected via LAN to fritzbox. All other devides have 0 issues with connection / stability.
The really strage thing is, after exchanging the device plug s with the warmwater plug s and reconfiguring the device plug (now controlling the warm water pump) the same way (schedule and auto off), it also has the issue, while the original warmwater plug s has no issues in the room below. I also tried different electric sockets that are closer and further away from the repeater with no differenz in result.
Had this issue from the beginning and with all firmwares, currently on 1.11.8 eco mode on.
Can it be a fritz repeater issue? I doubt its only a wifi connection, as the plugs becomes unresponive even to phsyical button.