This mod has been causing desyncs when a friend joins multiplayer. I think pausing the game prior to a friend joining helps the problem. On a headless, sometimes it prevents anyone from joining.

Thanks for reporting. I've never tested the mod on multiplayer nor expected that it will work on multiplayer. That said, your symptom may give me some insights on what's going wrong.

Unfortunately I won't be able to get enough time to test or fix the problem for at least several months.

The reason it desyncs in MP is because you're using local variables to store state data outside of functions.

That means when someone loads a game it populates those variables with data and then when someone else connects it re-populates them and they end up different on the 2 computers.

Simply store the data you use (between functions) in the global table and it fixes that issue.

aster26, do you know if the Desync issue has been fixed for Multiplayer? I was reading that this is/was pretty common error with some of the other mods, so the fix is out there!

I rewrote it and it now works in multiplayer: https://mods.factorio.com/mods/Lockhead/lh_eternity_trees