If another player is unable to join your hosted Warcraft III custom game on Battle.net, the most common causes are internet-connection sharing, a firewall blocking data, or a misconfigured router. Follow the steps below to address the issue.

  1. Make sure you have the latest software updates installed from your firewall provider.
  2. Make sure your firewall is properly configured to allow access to on all game ports.
  3. The game's default port is configurable and may have been changed. Follow these steps to check the current port in use:
    1. Start Warcraft III.
    2. Click Options.
    3. Click Gameplay.
    4. Locate Game Port. Make sure your software and hardware firewalls are configured to allow access to this port.
  4. Make sure you have the latest firmware updates installed from your router manufacturer.
  5. Configure the game port Warcraft III will use on each computer:
    • Example: Computer #1 can use port 6112, computer #2 can use port 6113, computer #3 can use port 6114, and so on.
  6. Configure your router to forward the ports set above to each corresponding computer. For example, if you set Computer 3 to use port 6114, forward port 6114 to Computer 3's IP address.

For more information on configuring your router, contact your router manufacturer. PortForward.com is a useful third-party site that contains port forwarding walkthroughs for most router models.