Forerunner 45s paired not syncing

Hi, Android 13 phone with forerunner 45s is paired but loses connection within a short time ie an hour or less. Then only way to get them to reconnect and sync is to reboot the phone or easier, switch airplane mode on for a few seconds before switching off. Phone and watch will then sync. But will lose connection in a short while and not reconnect without performing this action again.

Tried everything I can think of and tested again at each stage:

Deleted watch in app and Bluetooth before re pairing .

Reset watch

Deleted all data on watch

Cleared app data cache

Removed app from phone before reinstalling

Checked all app permissions are allowed

Battery optimization is off on app

I think this is everything I have tried, it seems to relate to Android with the above step resetting the phone but any ideas or solutions would be appreciated , thanks.