If you try to host a CiM2 online game and your friends get the error message "Connection Lost" when trying to join your lobby or if you can't see your friend's lobby even when trying to connect directly to the host IP, chances are your host is behind a router and uses NAT.
Unfortunately, the NAT Punchthrough does not work with every router so if you encounter this issue, you will need to manually set port forwarding so that players can connect to your server.
You can find a guide on how to forward a port with your router model/brand at the following URL: http://portforward.com/english/route...outerindex.htm
Cities in Motion 2, by default, uses the port 31183. You need to set this port forwarded to your computer address, both for the TCP and the UDP protocol.
If you are aware an application on your computer is already using this port, you can change it in the Misc configuration panel by selecting Settings>Misc from the main menu.