Failed to join stream: Screen share session is stuck on loading

[ImScheinox]

Hey, with the next update you will be able to set a custom port range for streams:

Allow Custom Port Range or Start Port for Screenshare Sessions

6.0.0-beta5 will provide a setting which can be found in the Developer Tools to set a custom port range.

Maybe that will fix your problems.
In the future, there will also be an SFU that routes the streams through the server instead of via P2P.