To play in a "LAN" style environment, you must use the built-in Multiplayer menu . While the game does not have a dedicated "Offline LAN" button, you can achieve a local-feeling experience by inviting friends directly through the Ubisoft Connect ecosystem. How to Set Up a Multiplayer Session
before the game transitions to local data transfer for smoother performance. Paradox Interactive Forums Multiplayer Setup Guide anno 1800 lan multiplayer link