LTE calls suddenly stopped working on Watch 3

[TNJGB]

This morning my watch 3 LTE was working fine and making calls connected remotely via O2 and my S21U. Suddenly whenever I try to make a call it asks if I want to connect using Bluetooth. The watch show as "remotely connected re02-UK" and it sends and receives messages via LTE-O2.  It still works if connected via Bluetooth.

I must have changed a setting on the phone but not sure what?

[TNJGB]

I have found a fix for this in that going into Settings/Advanced Features/Call and text on other devices then selecting the three dots, then remove device and removing the watch which was shortly automatically added in again.