That port is only for people to connect to from outside of the LAN (ie, on the internet)
You're more than welcome to set up a Vent server.
Also keep in mind that Mumble is better than Vent (because I said so
), and both TS and Mumble will be hosted at the LAN. (This LAN, mumble wont be hosted on my desktop, so it wont drop out every 15 minutes when I BSOD, nor will I BSOD this LAN)