Step 1

Click Start, then select Run. Type regedit in the text box and then hit enter. From the menu, choose "Export Registry File...", choose a File name, and select the "All" button in the Export range. If needed, you can later choose "Import Registry File..." and hopefully undo any damage. This is more of a CYA procedure, which I can't imagine anyone needing. At the same time, if something does go wrong, I'd like to leave you with a backup plan.

Step 2

If you're not still in regedit, click Start, then select Run. Type regedit in the text box and then hit enter.Navigate to My Computer, open the folder HKEY_CURRENT_USER by clicking on the plus sign.Open the branch labeled Software, open Battle.net, then select the folder labeled Configuration.

Right Click on the right side of the screen and choose "DWORD Value" from the pop up window.

Name this entry "Game Data Port"

Right click on the "Game Data Port" value that you just created and choose "Modify" from the pop up window.

Step 3

Here's the exciting part, you can enter in a decimal value for the port, such as 6119, or you can enter a hexadecimal value equivalent such as 17e7. The decimal entry is more direct, but it offers little challenge. It makes no difference which method you choose, since they accomplish the same thing. It's like comparing Celsius to Fahrenheit. If you choose to use decimal, select the decimal button. If you choose to use hexadecimal, make sure you select the hexadecimal button. You will want to use a value between 6112 and 6119. The Battle.LAN PDF (download pdf) that you should have downloaded earlier will provide you with the correct port values.

Click OK

Select Exit.