Hi
The following steps may help:
Reset the network settings on your iPhone:
- On your iPhone, go to: Settings > General > Reset > Reset Network Settings.
- You will need to re-establish your Wi-Fi connection afterwards, so have your password ready. Any VPN settings that were not installed by a configuration profile will also be removed.
Turn off cellular data on your iPhone, leaving your iPhone connected to the Internet only via your home Wi-Fi network.
On your iPhone, in the Watch app, go to: My Watch > General > Usage > Software Update - if an update file is shown there (it may not be), delete it.
On your iPhone: close the Watch app by double-clicking the Home button, then swiping upwards on the app preview.
Remove your watch from the charger and restart both devices:
- Turn both off together, then restart your iPhone first:
Replace your watch on the charger, keep your iPhone connected to power and try updating again by following the instructions here: