Hi @Elzuro
Your Xbox problem sound like the thread
UEFN Live Sessions Don’t Launch Onto Xbox One - General / Issues and Bug Reporting - Epic Developer Community Forums (unrealengine.com)
Only the latest versions of Fornite for Xbox automatically update.
The error you have was fixed in recent update of Fortnite
In the bottom left should see 31.00 [35447195] Every time the game goes to lobby.
In 31.00 when UEFN connect you get message in the top left saying “UEFN is joining your game”
If you do not have that on your screen you need to manually update as described in thread
Thanks