My friend and I are trying to play Warhammer 40k Retribution together in campaign coop. When one of us accepts the others' Steam invite, the connecting player sees "Connecting..." then "Connection timed out". The other player sees no indication that anyone is connecting.
We're on a lan, both connected to the same router. Both of us have version the latest version currently (3.12.05944), both of us have all firewalls disabled on our machine (though we're behind a NAT). The NAT does support uPNP.
Any help is greatly appreciated.