No it will communicate with the router once power is restored. There is a much bigger issue though with the Wemo light switch. Once you link it to your network it is never erased from it. it you would rmove it from your wall box and give it or sell it to someone across town or anywhere, once they put in on their network and go outside with the phone app they will be able to see all your other Wemo devices in your home. The switch stores the network name and password and does not erase it. I know this because i bought one, linked to my router. i did not have as much use for it as i though and a friend of mine needed one. I removed it from my electrical box and took it to his house miles away. After we got it hooked up we went outside to see if the app would work. All of MY other Wemo devices appeared on my friend's phone. The 2 networks got crossed up. It is Cloud problem. He not only could see my devices he could turn them on and off and set any schedule as well. it took weeks and multiple calls to finally get their Cloud technicians to fix it. talk about a security flaw. Belkin knows all about this issue. i think it has been present since they launched the Wemo Light switch. You really can't sell it to anyone else unless you have no other Wemo devices in your home.