Things You'll Need
Instructions
Power down your router and all of the devices connected to it, including any modems, consoles and computers.
Connect two or more PS3s to the router with the ethernet cable. Place one end of the ethernet cable in the back of one of the consoles, then the other end into the router. Repeat this step for each PS3 that you are connecting.
Turn on the router and connected modem. Wait while the router initializes and connects to the internet.
Power on both consoles and load up the game you want to play. You must have a separate copy of the game for each system.
Select the LAN option in the multiplayer menu of your game and search for other PS3s on your network. All systems connected to your network should show up, and you will be able to play system link over your LAN connection.