found this maz
sounds alot like your issue, and not too bad to fix
If you are having trouble loading Call of Duty: World at War (CoD 5) games via LAN and are forced to use manual IP addresses, it is likely due to the game's inability to automatically broadcast or discover servers on your network, or because of conflicting network adapters
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Here are the tested fixes for this issue:
1. Fix LAN Discovery (Set Net Port)
Often, the game fails to establish a proper LAN handshake, requiring you to force the port.
Open the console in the game using the ~ key (tilde).
Type: /set net_port 28961 and press Enter.
Type it again to verify the output shows: net_port 28960 -> latched value 28961.
Have all players do this, then try to see the lobby.
2. Disable Virtual/VPN Network Adapters
If you have VirtualBox, VMware, Hamachi, or a VPN installed, CoD 5 may be trying to use those network connections instead of your actual LAN/Ethernet connection.
Go to Control Panel -> Network and Sharing Center -> Change adapter settings.
Disable all adapters except the one you are currently using (e.g., disable Wi-Fi if using Ethernet, disable VirtualBox Host-Only Network).
3. Check for Firewall/Antivirus Blocking
Windows Firewall may be blocking the game from acting as a server, even on a local network.
Allow the CoDWaW.exe or CoDWaWMP.exe through Windows Firewall.
4. Direct IP Connect (Alternative)
Since you are already comfortable with using IP addresses, you can force the connection in the console, which is sometimes more reliable than the lobby browser:
Host opens the server.
Clients open the console (~) and type: /connect <HOST_IP_ADDRESS>.
Summary of Common Causes
Multiple Network Adapters: The game gets confused.
Port Conflicts: Using the same port (28960) for multiple computers on the same router.
Firewall Rules: Blocking the game's ability to broadcast.