New wife - can’t add back any nest protects

[Zzzzz2]

Changed Wi-Fi network with new router and all nest protects went offline. Impossible to reconnect any of them. Keeps asking for an assisting device, but everything is offline except the thermostats and that doesn’t seem to qualify. Why is it necessary to have an assisting device? What if this were the first device I was installing? 

[ClaptonDad]

I’ve had exactly the same problem. The app can’t connect to any of the devices. I tried removing one of the Nest Protects but now can’t add it back. I get the blue circle on the detector but the app can’t connect to set it up. Help!

[Zzzzz2]

Had to delete every protect from the home and factory reset each one. Then was able to add back one at a time with the first one added becoming the “assisting” for the following adds. It did not ask for “assisting device” on the first add back