dogwithrabiez :
Wait, just so I'm getting this right, even if I forward my ports and/or set UPnP on, I'm not going to be able to play both at the same time?
I tried setting UPnP on before. Didn't work. Strangely enough though, we were able to play once with the router set on default settings(meaning UPnP off and firewall on), but were unable to any other time.
Does Bad Company 2 allow the port changing?
If you have two machines behind a NAT router that both require the same ports to be opened and forwarded, you can't do it. Period, no way, no how. There's simply no way to disambiguate traffic received at the router's firewall on port "X" and decide which of those two machines the traffic should be forwarded to.
When port forwarding, the port # is essentially a proxy for a local IP address (port 2190 = 192.168.1.100, port 3188 = 192.168.1.45, etc.). But once you add a second machine, unless you can use different ports, you’re stuck.
And no, you can’t use port forwarding for one machine and place the other in the DMZ. Put yourself in the position of the router. Given traffic at port X, should it be forwarded to the machine designated in the port forward, or dumped into the DMZ? There’s no way for the router to decide. So the traffic for that port will ALWAYS be forwarded to the machine w/ the port forward. And pretty soon everything’s a mess. The machine w/ the port forward is getting its own traffic AND traffic intended for the other machine, meanwhile the other machine is completely starved!
You face the same dilemma ANYTIME you need to support services behind your NAT router. Imagine two ppl in your home wanting to setup their own web servers. The default port is 80. However, only ONE of you can use that port. The other must use something different (81, 8080, 8081, whatever). Fortunately that easily solved since a web server will always give you the option to change its default port assignment.
As I said, you *might* be able to either change the ports used by the game or change the NAT type (and that would almost surely limit your features). Unfortunately, I know nothing about BC2 in this regard.