VPN connection

Hi, I'm trying to setup a VPN connection. On my mac mini I have the server application. In all the guides that I've found always people configure the router with utility airport, but i can't see the mine through this application because this is vodafone station, not an apple router. What i should do? I've already opened the TCP/UDP port in the router and configured the VPN in the server application, but it still don't work. thanks