Apple Watch series 7 update and pair fail

My Apple Watch series 7 once stopped receiving notifications, calls etc. from my iPhone 14 pro. I decided to unpair them thinking that this would solve the problem. Now they fail to pair from time to time, but if they pair, then it asks me to update my Apple Watch to the watchOS 10.3.1. I follow all the instructions, but after preparing an update it fails for no reason. I cannot set up my Apple Watch without an update, and I cannot update my Apple Watch also for no reason. Is there any way to solve the problem? I have also tried restarting my Apple Watch, but it didn't help. My iPhone 14 pro is updated to the latest iOS version. I have run out of all the possible causes of the problem. Thanks in advance.