Can someone help me, every time I try to join my friend's party after waiting a while this message appears, does anyone know how to solve it?

[Braboerick]

[hindercanrun]

Braboerick host needs a open Nat type

[Resxt]

Get him to join your party instead.
If it doesn't work then one of you has to open port 3074 (UDP) in his router, for this see Google
Then the one who opens the port invite the others