Unspecified Error

So I have a very annoying Problem and I hope
someone can solve it because I don‘t know what to do. I tried so many thinks but all of them didn’t‘ worked.

First of all some Infos.



-Build: 16858.2145458


-Reproduction Steps and what I (and my friend) already tried

-Me and my friend enter the Game
-we made a lobby (both of us more than two times)
-both of us become the following Message,,Unspecified Error‘‘
-he restard his Pc (It worked)
-I restard the Pc (It didn‘t worked)
-I repaire the Steam library more than three times (it didn‘t worked)
-I De an Reinstall the Game (It didn‘t worked eighter)


-Picture from the Message:



(Sorry, but i write this on my mobile phone)



-Host in Campaign (Me):



(Nothing to see. My friend can‘t simple join me)


-other infos

-we installed no mods or something
-I have 140 hours but never played online so i realised the error first, after we try to play together


I really hope someone can help me
and thanks for reading this wall to help me out. UwU