Software update impossible on Series 2 SE watch

After OS26 failed to install on SE series 2 watch discovered it was still paired with previous iphone. Then followed steps to unpair with old phone and tried to pair with new iphone 13. Pairing failed with the message that watch needed to be updated with latest software first. The OS26 download typically take 2 hours eventually but then cannot be verified because "you are not connected to the internet"

Have tried all official support suggestions without success.