[0.17.79] Can't establish connection to server

[-DOWL-]

I can't join multiplayer games, nor can people join games I'm hosting because the game "Cannot establish connection to server". I've tried what has been suggested in other threads but nothing seems to work. I've enabled DMZ and port forwarding but I'm not sure if these settings are correct.



Edit: I forgot to mention that I can connect to some servers, only dedicated servers it seems and not those hosted by my friends.