JorgeB

Static is typically more reliable; post the diagnostics or persistent syslog after you lose access.

That suggests there's still a filesystem issue, reboot, try accessing via shares again, and post new diags.

If it's just with a specific container, look for its support thread, in case it's a config issue with it or a known issue

Hardware is fine, could be a problem with the client NIC (or its driver or the OS), cables, etc.

Would be very surprised, considering there are multiple unrelated apps crashing, but you can try downgrading and retesting.

I see an i5 13600K, this would be my main suspect, lots of users with this and similar CPUs have stability issues due to the Intel 13/14 gen issues; some users are on the 3rd and 4th CPUs.

Check the emulated disk contents, and the lost+found folder like trurl mentioned, and if you are happy with the contents, you can rebuild: https://docs.unraid.net/unraid-os/using-unraid-to/manage-storage/array/replacing-disks-in-array/#re-enabling-a-disabled-disk-rebuilding-onto-itself

Scrub the pool and post the output from the GUI

The used/free on main will be correct, cpacity is incorrectly reported in this case, this is a btrfs issue.

There's a controller with SATA port multipliers; these are not working correctly with the latest kernels, and they are never recommended anyway. Recommend replacing it Recommended controllers for Unraid - Storage Devices and Controllers - Unraid

Got around 700 or 800MB/s last time I tested

No, but the usable space is the same as the smaller device.

Delete/rename /config/network.cfg on the flash drive, then reboot Unraid; that will revert to default DHCP settings.

If the Unraid server is using zfs you could use zfs replciation, or you can use this for example (any filesystem) https://forums.unraid.net/topic/97958-rsync-incremental-backup/

If it starts in safe mode it suggests a plugin issue.

Is that after booting Unraid or with the USB Tool? The latter doesn't show the GUID for some flash drives.

root is to access the GUI only, you must use one of the other users for SMB shares

Yes, that should work.

If the pool name started with mirror that is not allowed now, since it's reserved. Add a new pool with an allowed name, assign bot pool devices, leave the filesystem, set to auto, and start the array to import the pool.

Emulated disk1 is not mounting; check filesystem on it.

You can just use it as a normal pool.

Random reboots are almost always a hardware issue, start by running memtest from the boot menu, or because memtest is only definitive if it finds errors, if you have multiple sticks try using the server with just one, if the same try with a different one, that will basically rule out bad RAM.

Tailscale is also a good option IMO.

You can still share the pools using disk shares (if enabled)

That suggests a specific issue with that VM or vdisk, it may not be easy to troubleshoot. If you can, copy the data to the new VM and start using that one.