I have a series 2 iWatch and learned 6.1 was out. Apple reported it would run on series 2.
When I tried to upgrade; it kept timing out and reporting there was no wireless network.
Usual diagnostics didn’t work. I power cycled the iPhone and iWatch. It worked for a little bit and then the same problem.
The upgrade process requires the iWatch to be on a charger. This is only for the actual install phase. I decided to leave the iPhone and iWatch with the wireless router over night.
The next day I found the download had completed and of course it would not install since it was not on the charger.
After the iWatch was on the charger; the install ran for about an hour.
iWatch now has 6.1.