Anno 1800 Lan Multiplayer Fixed

This open-source tool patches the game’s memory at runtime to:

How to use:

Verdict: This is the gold standard for LAN parties. It works even without an internet connection, supports up to 8 players, and has lower RAM overhead than the official method. No desyncs reported in 2026 tests.

| Error Code | Meaning | The LAN Fix | | :--- | :--- | :--- | | Error 0x800401 | Relay server timeout | Switch to Direct Connection. The host is trying to use Ubisoft servers. | | Desync (CTD) | Packet loss | Check your Ethernet cables. Disable WiFi on both PCs if hardwired. | | "Unable to join" | Port 18000 blocked | Manually forward ports OR disable Windows Defender entirely for 5 mins to test. | | Endless Loading | IPv6 conflict | Disable IPv6 on your Network Adapter properties. Force IPv4. | anno 1800 lan multiplayer fixed

Here is the definitive tested method for a 2-4 player local game with zero internet dependency:

In late 2022/early 2023 (depending on your region), Ubisoft Mainz rolled out Game Update 17. Buried deep in the patch notes was a line that brought tears to the eyes of cooperative builders: "Improved network stability for local peer-to-peer connections."

While no one at Ubisoft explicitly said "We added LAN," dataminers and network engineers quickly realized what had changed. The game’s reliance on the external relay for initial handshake was reduced. The game now prioritizes a direct UDP hole punch on the local subnet.

Is it fixed? For 80% of users, yes. For the remaining 20% (strict corporate firewalls or misconfigured VLANs), it remains problematic. This open-source tool patches the game’s memory at

For those who want LAN over the internet (virtual LAN for remote friends) or have complex network setups (VLANs, multiple switches), the ZeroTier method remains robust:

This isn’t a “fix” for local LAN per se, but it transforms any network into a LAN—perfect for dorm or office play where IT restrictions block local discovery.

Sometimes, the game tries to fall back to the internet even when you don't want it to. This forces it to stay local. How to use: