I've had a working system for over a year. The other day I had to unplug the main Deco. It came back up flashing blue (with all satellites blinking red). I set it all up again and it worked fine - but

Just updated my Decos and now one of the three will no longer connect to the others. I tried moving it next to the main one, no luck. I tried making it the main Deco but it flashes red and will not co