Every so often (~1 per month) my watch refuses to communicate with my phone even though it shows as connected on both the phone and on the watch.
Nothing that talks to the phone works - Sync, Weather, my own app etc.! See attached video.
This problem has persisted since the watch was new and through all watch updates and a new phone (Samsung, Android)
The only fix is to restart the phone (restarting the watch doesn't fix it)