Certain friend can't join any server on any game that I host

Whenever I host a server on any game, Rust and Garry's mod most recently, one of my friends can never join. He is doing everything right to connect, and he can join ohter hosted servers. Also other friends friends and players can join my server

 

He received the error "timed out" but I get in console that his steam auth ticket was cancelled, other players in other networks can join.

 

He is able to join other servers no problem.