FP3 Wifi-Calling no longer working

/e/OS Devices Fairphone
3

I called my provider (congstar), they checked everything and told me it’s all correct and Wifi-Calling should be working. I also made a Wifi-Call with my SIM in another Phone. It worked.

I think it must be my phone because wifi-Calling stopped working directly after the update from 1.4 to 1.5 (Android 10 to 11).

I fould these two posts from other users:
https://gitlab.e.foundation/e/backlog/-/issues/4850

https://community.e.foundation/t/when-trying-to-use-wifi-calling-while-connected-to-wifi-phone-asks-to-connect-to-a-wireless-network/37772

If there is a bug then I wonder under what circumstances it appears, because I doesn’t seem very spreaded.

Is there a way to compare ALL for Wifi-Call necessary settings of the FP3? … including permissions and the “advanced privacy” settings?

Thanks for your help.