Verified answer

Commandos 2 uses Microsoft's DirectPlay for Internet/LAN Play. In order to play Commandos 2 Multiplayer through a Firewall you will need to open ports 2300-2400 UDB/TCP inbound/outbound and 47624 inbound/outbound.

Commandos 2 Multiplayer

Hook yourself to the net then click multiplayer mode then play. If it's your first time, don't fret if you're not that good at first because even people of the highest prestige at the highest level can get crappy scores because it's sometimes dependent on luck and your team's strengths.