Port Forwarding

This article is persistant and should be accurate for any version of the game.

The game uses UDP hole-punching to get past router firewalls which works 90%+ of the time, but some routers are freaks that don't allow it (Symmetric NATs). If you want to set up port-forwarding see below.

The default port used by servers is 5728/udp. The client will try to use the first available UDP port from 6000 to 7000. Both the client and the server will use port 80/TCP (http) for, for example, looking up the server list.

Be sure to allow vtclient.exe

and vtserver.exe
are permitted to get passed the Windows firewall!

Ports

Forward 5728/udp for the server

Forward 6000-7000/udp for the client

Links

How to set up Port Forwarding on a Router (WikiHow)