Portforwarding

A Port is the number called by the player trying to join your game, if it is closed then they cannot join your game. When using a modem/router that has NAT you must tell it to open the port and send the traffic to the right computer, which is the forwarding of the port.

6112-6119 TCP/UDP

A misconception is that all ports need to be forwarded and that means 6112-6119 UDP and TCP but that's not true. Blizzard games can only use one port at a time and this is by default 6112 unless otherwise set in Regedit "Game Data Port". Now if you're wondering why 6112-6119 ports are all suggested, it's because Blizzard thought ahead when they made Battle.net, it's a range that can be used on one local network to use multiple computers so that everyone can host without any problems (now on the official blizzard servers you can only use the 6112 port, on ours you can use any) and this means that all traffic passes through the host, see the picture below. When a host comes out one random player takes that responsibility.

How to Portforward?

It all depends on your configuration, there are different combinations such as modem->router->pc and modem/router->pc, as well as CGNAT->modem->router->pc and CGNAT->modem/router->pc. CGNAT is Carrier Grade NAT, which will prevent you from portforwarding altogether.

The modem->router is a little harder to forward because you could be behind 2 NAT (firewalls), which means that you must first forward the modem to the router and then from the router to your PC's IP address. You only need to forward port 6112 UDP through to your PC's IP address. You can find the IP address using CMD ipconfig /all or go to Network and Sharing Center > Adapter Settings.

Once you have portforwarded it is necessary to test your ports. First enter our server and type /netinfo , then you should see your IP:Port (Port 6112 is the default) which means that the Game will use that port if it is something else you are not fowarded or portforwarding will not work for your setup. Go to this page when you are in the chat lobby or in a game it doesn’t matter. If it turns green then everything is fine and the ports are fowarded. There are many different modems/routers and each is a little different from the others so it is best to read the manual of your device or go to YouTube or portforward.com to find more precise instructions.

Game Data Port

Simply put, the Game Data Port is the port you specify for the game to use. This is used if you want the game to use ports 6113-6119 instead of port 6112. To get started open regedit and navigate to HKEY_CURRENT_USER \ Software \ Battle.net \ Configuration for the CD version or for the GOG version HKEY_CURRENT_USER \ Software \ Battle.net \ D1 \ Configuration. Once there, Right-click > New > DWORD (32-bit) Value, then name it Game Data Port. Then Right-click > Modify and choose "Decimal" Base. Value data: 6113. Log in to the server and check if your game uses the port you set using the /netinfo command. If everything is OK stay in the lobby and go to this page and check you port. If the result is green then you are ready to host.