This is driving me insane. I'm trying to move my hosted realm to a VMWare VM locally so I can run Dynmap. The problem is the server will run for a while without a problem (Couple days to do the dynmap render, log in and bounce around for a couple hours here and there marking landmarks), then start freezing the entire VM on login to the game. The only way out is to hard-reset the VM.
I've had this on Ubuntu and Fedora. With openjdk and Oracle JDK. With vanilla server.jar and spigot-1.16.4.jar. With and without the Dynmap.jar present.
On this latest Fedora attempt, the minecraft server and world files are in a zfs dataset so I can have snapshots like on my hosted realm, and rolling