Whether you’re playing on a literal Local Area Network (LAN) or just trying to get a stable co-op session running through the internet, here is the comprehensive guide to fixing multiplayer issues in Anno 1800 . 1. Fix Connection & Invitation Errors (LR05, LR39)
A common fix for "failed to connect to remote IP" (LR39) is to disable IPv6 on your network adapter. This forces the game to use the more stable IPv4 protocol.
All players must have identical game data. Use the "Verify Files" tool in the Ubisoft Connect or Steam launcher to fix corrupted assets.
Ensure your router allows traffic on UDP/TCP port 18000 , which is the official port for Anno 1800's multiplayer services. 2. Solve "Desync Detected" (LR40) and "Trajan" Errors