Anyone else have an Ultra that just out of the blue says it lost Internet and simply restarting the device brings it all back leading me to believe it has zero to do with Internet connection.
See if this helps - it has worked for me numerous times:
Restart your router (even if other devices have no problem finding and connecting).
After the router comes back up, restart the Roku via Settings > System > System restart (for a Roku TV it's Settings > System > Power > System restart) to start with a clean slate.
Reconnect to your network.