Before we fix it, you must understand the enemy. The LAN feature in War in the North was built on Games for Windows Live (GFWL) architecture, even for local networking. Even though you aren't logging into GFWL for LAN, the handshake protocol relies on deprecated Windows services.
Three specific issues break 3-player LAN today: lord of the rings war in the north 3 player lan fix
Here is the step-by-step fix.
A. Windows Firewall You must allow the game executable through the firewall on all 3 computers. Before we fix it, you must understand the enemy
B. Router Port Forwarding (If using a Router) If you are playing over a VPN (like Hamachi) or a strict local router, you may need to forward the port to the Host PC. Here is the step-by-step fix
Uninstall any existing Visual C++ Redistributables (2005, 2008, 2010) and reinstall the original versions from Microsoft.