Watch OS8 will not install

I have a series 4 Apple watch running OS version 7.6.2. My iPhone 11 is running OS version 15.0.1. The watch battery was fully charged and was on the charger when I tried these options. On every occasion (and after roughly 30 mins) the result is the same - "Software Update Failed An error occurred downloading the latest version of watchOS on your Apple Watch." The iPhone was sitting next to the Watch, both were connected to wifi and close to the router.

I have tried unsuccessfully to install OS8 as follows:

1. Update from Watch app.
2. Remove virtually all installed apps from the watch and update from Watch app. (My watch has 9.3 GB available.)
3. Power off the watch and the iPhone and then power up and install from Watch app.
4. Power off the watch and the iPhone and then power up and install directly from the Watch.
5. Restore the watch from backup and install from the Watch app.
6. Setup Watch as new and then update from the Watch app.

Suggestions please. Thanks.

What model of phone is it and what version of ios is it running?

What model of watch is it and what version of WatchOS is it running?.

What troubleshooting steps have you tried?.

What errror messages are you receiving?.

iPhone 11 Watch series 3 …I am attempting to install update OS8 and have watch on charger, fully charged and next to phone connected to wifi. Get message “unable to install update, an error occurred installing the latest version of watch is on your watch”

how can I resolve this ?

Make sure that is connected to wifi

Watch version 7.3.3 iPhone version 15