Pair a series 6 watch with a 16 pro phone

Setting up an old watch with a new phone & the process has been more than frustrating. It shouldn’t be this difficult! I fear it is designed to make me buy a new watch. Last night supposedly my watch paired successfully. This morning my new phone & watch didn’t appear to be talking to each other. I shut my watch off & then my phone. When I turned them on it asked for the watch to pair again. Now it keeps coming up saying it can’t connect to the server. Why is this? I shut my phone off & on again but the watch won’t turn off.