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.
: If using mods, every participant must have the exact same version and files installed to prevent crashes. 🕹️ How to Start a Match anno 1800 lan multiplayer
Despite the lack of native support, the PC gaming community has developed workarounds to simulate a LAN environment. These solutions primarily aim to allow players who are on the same local network to bypass internet routing bottlenecks or to play with friends who own the game but cannot connect via official servers due to NAT (Network Address Translation) issues. As of the final Season 4 updates, Ubisoft
Don't try to keep playing; the game states have diverged. : If using mods, every participant must have