Same problem here for hosting non dedicated ONLINE CAMPAIGN COOP....
Same can not connect error.
Same "happened upon unknown error".
Same 1,2 and 7 maps loading fine.
Same for 6 other members of my clan who bought this game.
Same lets blame something else other than the patch responses!
Worked well, excluding bugs, under 1.2. Added the patch and now left with 3 of 10 campaign coop maps to play.
Haven't tried LAN yet but hoping, no preying, it will work via Hamachi online LAN software.
If you can HOST the other maps in CAMPAIGN COOP then please acknowledge it and where