Cannot update new Apple Watch while new pairing with Iohone 12

After receiving a replacement iPhone series 4 watch ordered via phone order thru Apple Support,  I attempted to pair with my iPhone 12 max (with latest update) but could not update the software on watch. I kept getting messages that the iPhone could not connect to the Internet. I was told by Apple Support that I now needed to bring the watch and iPhone to the Apple Store to see if Genius Bar could update the watch software otherwise I would have to return the Apple watch again. It seems from search that this issue has a history since 2017. Is there another technical  “fix” for this I’ve not been made aware ? I waited a week to receive the replacement watch and my next available apple store appointment isn’t until Friday. He said if store can’t update I may have to mail back this “new” one too .