@jra11500,

Is there a possibility that the Range Extenders are too far from the Main Router? Range Extender falloff is a real thing and only a few feet or sometimes inches can cause issues with the connection. We always recommend placing the Range Extender in a location with a strong signal, as the signal at the RE will limit your other devices.

There is also a difference in the way that the REs behave when there is a power issue that affects the entire house, rather than simply losing the network. When the power goes out, the devices will immediately cease trying to connect to the network, and will resume after they boot again. This means that if the power were to go out for your home, then all of your network devices would be brought back online at the same time and should be able to connect to each other when the power is restored.