PC [HELP] Unable to connect to a Friend

[Varo]

No matter who hosts, we cant join eachother on steam, we cand send the invites, we tried everything from de troubleshooting, we cant join

 

[Magically Clueless]

Do you only see LAN when you go to the co-op screen? Is there anything else that sticks out to you when you try to join your friend's game (or vice versa)?