Anno 1800 uses a frame-locked simulation. If Player A's PC calculates a trade route profit differently than Player B's due to a micro-stutter or high ping, the game desyncs and forces a reload. LAN eliminates this almost entirely. You can play a 20-hour save file without a single rollback.
: Every player must launch the game while connected to the internet and ensure the "connected to matchmaking" icon (a green icon on the mid-right of the screen) is active.
As of the final Season 4 updates, Ubisoft has not touched the LAN infrastructure, which is good news. It remains stable. However, be aware that the upcoming Anno 1800 console ports do not support PC LAN crossplay.
