Cannot re-pair with android phone after 17.23 update

After every update I have the problem that I cannot connect my Fenix 7x Sapphire Solar to my phone anymore. Each time I have to go through the procedure layed out by Garmin to reconnect the watch via the Connect App.

https://www8.garmin.com/manuals/webhelp/GUID-C001C335-A8EC-4A41-AB0E-BAC434259F92/EN-US/GUID-4442F808-670B-4EF3-AC60-32666F173DFD.html

After the 17.23 update, this approach does not work anymore. I do not get to the pairing screen with the QR code but stays in "initialising" until it times out. The watch cannot connect via Bluetooth and WiFi (when serching for WiFi the watch cannot find any networks) - I can connect via cable and Garmin Express.

I have done

1. a factory reset

2. a downgrade to 16.22

3. a reinstall of the last backup that worked.

Nothing allows my to reestablish the connection.

Please help