Hi Casey,
I'm not familiar with Trackman so I can't give you a specific answer.
I can, however, give you a few general hints.
If you want to connect to the server obviously you would have to be on the same network and the ports should be open on the switch. Try pinging the server first to see if you have a connection to the server. If you can ping but you can't connect then most likely it's an issue with the port. You can also use a tool like TelNet to try and connect to the port too.
By default all connections used in Datalinq are TCP I believe, but maybe there might some option to use UDP as well. TCP and UDP are quite similar except UDP doesn't allow two-way communication.
Another approach would be to use a serial-to-USB convertor and then hook that one up to a USB-extender which can be connected to the XPression. Ofcourse that would mean that there are UTP-tielines between the XPression and the Trackmen-server. Those tielines cannot pass through a switch or it will (probably) not work.
Good luck!
#XPression