Project Cartographer Local Multiplayer Not Working [LAN]

Not sure this is even the right place for this. I can't find a single forum post anywhere that can help.

Project Cartographer is great. I am still trying to understand the Network and Multiplayer apsects of it and perhaps I am missing something.

Here's what I got:

Two or more machines on a LAN, that's local, same building, same router, same room even. One machine selects "Create New Game". Enter confusion. How do I invite peeps? Now, on the OTHER machine(s), I can see the session on the server list in "Pre-game". When I try and join, it fails. Can't seem to connect to my own game, on my own LAN, with my own machines. Is this beyond the design of Project Cartographer?

Steps I have taken: created OpenVPN subnet, used the VPN tunnel adapters as the Network adapters to connect with in each machine running Halo 2. Funny thing is the servers are still listed in the browser even though I have chosen the tunnel adapters.

Anyways, to summarize, what steps are necessary to host a closed multiplayer session on a local network (non-wan)?

Thank you for your time and consideration.

- raedeus