I finally got an answer from Arno from homey and everything works fine now!
The solution was: disable router and WiFi, unplug the Bridge and replug it. It then looks for a known WiFi and since that is missing, it automatically goes to setup mode with bluetooth and the pulsating blue ring. Then switched router and WiFi on again and added the Bridge in the Homey App again. That’s it!
Thanks for all your in put and help!
Thomas