I just had a MP provided server for ARK, but on the last update the server stopped working and it couldn't get resolved so my friends opted to move providers. As they ran it from the same saves and worked without issue we tried to figure out how it worked. It appears the last update made areas around the volcano's a no build zone. But as it's not removed within the game update it caused the server to currupt. The provider we are with now does remove items in these areas, which are now marked with a circle that indicates if you are good (green) or not (red).

While we are not able to test this for our selves. I wanted to share this in case someone else is suffering with this issue and it can be resolved and help MP retain people who have servers.