My buddy and I have been playing Vintage story together since 1.17, with him doing the hosting (and playing) from his own PC. His PC is running Linux, while I am running Windows. This has run very smoothly until one of the first updates of 1.20. Ever since then only the host has issues that to us look like severe lag / latency issues; blocks not being places correctly, mobs not taking damage, in general interactions being severely delayed or not occurring at all. He has also reported situations that where he performs actions but after relogging the action has not been performed, or has been performed but he has nothing in his inventory.
So far this seemed to have been triggered mostly by him opening the map and looking around a bit, however we have also noticed that if I do a lot of exploring he also suffers from it. In these situations he can resolve it by leaving the game and rejoining, however it is only a temporal fix before he starts getting the issues again. We hoped that with map performance upgrades of 1.20.11 the issues would have been resolved, but so far it didn't seem to have helped any bit for him.
Last session we both got our first ridable Elk, and ho boy is he having issues with it. All the issues he had before are much more noticeable when riding the elk. Like situations where on his end he has stopped riding the elk but for me he is zooming by, and when he relogs he actually is where I saw him go towards. Similarly I also noticed that for me he keeps doing moving animations when in place, but I am not entirely sure if this is related or is a change 1.20 has introduced.
As mentioned before, what is odd to us is that it is just the host is suffering from these issues. In every situation he gets these issues I have zero problems. Similarly it has worked fine before with previous versions of the game on exactly the same machine. He has checked multiple times if it is an issue with his PC running out of RAM while running the game, but that is not the case (he has 32GB of RAM). Similarly we have ruled out any internet issues because then I would be the one suffering, not him.
We only have a couple of mods running:
Chisel Tools
Expanded Food
A Culinary Artillery
Auto map markers
Resin on all sides
Prospect Together
Better Firepit
HudClock
The only one we suspected of being the culprit of this list is Auto map markers, but even after disabling that mod the issues persist.
I've looked around on the forums and bug reports, but so far no-one else seems to have reported any similar issues, hence I wanted to check if this is the case.