yup
download the pinger from destructor.set a fixed ip on your server(i explain in ppost below how).set this ip adress in ur router like a dmz (all ports open)or set a virtual server with open port 17479.on your game pc pinger refresh and u see ur server i hope.rite click on it and select add internal server.now appears below and should have green lite wich means routed correctly.
join.have fun
i hope u understand ur though lol.
what causes it is nat protocol.u get the ip adress from provider. router takes it in. isp server thinks the router is the pc.the router makes sub ip adresses wich are invisble for the outside.the problem it causes is also the outside will go to the ip adress in the router.wich is not your gameserver.so the router then must send everybody to that internal ip adress.
anyway back 2 work gl