Cant host or join co-op server

Game mode: [ Co-op]
Type of issue: [ Bug ]
Server type: [ PvE ]
Region: [ EU ]
Mods?: [ No ]

Bug Description:

I cant connect to co-op server so i tried to host but same error happened
it says “attempting to join game”
then “Could not connect to server. Your connection to the host has been lost.”
same happened to my friend too

Expected Behavior:

Join normally.