Play multiplayer on same ip?

[Deadman]

Me and my bro want to play cod4 multiplayer using same wifi and on same server but at a time only one of us can connect to a particular server. Any help?

 

[gameranand]

The problem is that both are computers are having same external IP address through which the server detects you. That is why its only allowing only one PC to connect. You need to make Sub-IP address to connect to the server.
Assuming you have it on Steam
Configuring a router for multiple clients

If not then this link should clear your doubts
Connect 2 computers with same IP to same server? - Routers - Networking