In a fairly long building, I have 3 Deco M5s in line. The main one at one end of the building, the second one in the middle and the third one at the other end.

The one in the middle regularly (two or three times a week) loses connection with the main one (the LED flashes red). Of course, as a result, the third, which depends on the second, also loses the network.

Simply unplug the second Deco, then plug it back in, and the third Deco is back on line.

What could cause the second Deco to lose the link and not regain the network on its own, without having to disconnect it electrically?

Thanks for any idea