Tiny Tinas Wonderlands Coop Problem

my friend also plays xbox and I on epic. the connect to me does not always work and when we are once in it flies immediately or after a few minutes always out again.
he has probably already tried with someone else and there is the same problem.
has shift or xbox any problems. since the coop here had / has quite a few problems ne question if it is being worked on? and if so how long already / still?
I have unlocked ports as host and tried all other tips. crossplay is also on but nothing helps.

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