Faced same issue, solution that I found worked is to find Disable UDNP, make firewall rules for outbound and inbound connection allowing 27016, then have the host type in "ipconfig" into command prompt to get local ip/ipv4, then connect in game with the (shift)-tilda console. IE: Connect 10.0.0.250 . IF the client immediately gets the cod loading screen it worked, else no clue.