OK, so I am having this problem. I have read through a lot of this thread. I have a Mac that i think is running Snow Leopard along with an Actiontec MI424-WR router. I can make dedicated servers, but i can not join them. I host it on the same computer I use, and I would just like to get this over with. I will supply any info needed. Thanks.
Again, I will bring up the pointlessness of this thread; the tutorial on here is actually for the Airport series of router, not for all routers.
For your router, you can port forward using the standard method of IP address into browser. See
here. However, technically you only need to enable UPnP, some routers come with this enabled by default, I'd suggest you see if someone else (not in your LAN) can join your server.
The issue of you not being able to join your own dedicated server, even if your dedicated server is an Online one, I believe you will need to join by the Query LAN (rather than Query Internet) interface (as you are in your own LAN).