Long time android tv user thru Sony Tv's. Just bought the shield and wow speed is insane! I set it up thru my Google account, and the Ethernet is plugged into my router that is the wifi that my phone and tablet use. I keep getting error when trying to add shield as a device to cast to I'm Google Home. Is casting Wi-Fi only? I thought as long as it's plugged in to Wi-Fi router it should work. Thanks for your responses.
I had a similar issue a while back. I found deleting the app data/cache for the Chromecast app (can't remember what it is actually called, sorry) followed by a restart did the trick.