Shelly Gen2 devices crash and I don't have a clue why it happens

Hello, I have 2 covers in a big window, so I've purchased 2 motors and 2 Shellys Plus 2PM to control them. Since I'm using Home Assistant, I've integrated them with the official built-in integration, and created a "cover group" to manage both covers as if it was only one.

Furthermore, a year and a half ago, I bought 2 Shelly Plus 1 to control a pair of lights, also with Home Assistant.

My problem is that from time to time, one of the devides (or sometimes both) crashes and stops working connected. The relays still work on manual switch operation, but the device is unreachable, can't be pinged, it's unavailable on home assistant, can't connect via Shelly App with the Cloud and can't acces via web UI. It's solved cutting off the power and turning it on again.

This is happening maybe each week, maybe each month, or maybe each two months, sometimes to one device, or maybe to other device. I don't understand why, in the case of the Shelly Plus 2PM, both have exactly the same use, but this weekend one of them crashed and the other was fine.

Since my problem with the Shelly Plus 1 is older, I tried to configure them with a second WiFi Network (my smartphone's shared AP), to see if it was a connection issue with my router, but still I couldn't connect to them when they failed.