JorgeB

You can use for example rsync over SSH.

Looks like the OOM is being causes by Prowlarr, it was using a lot of RAM, I assume the RAM usage is already limited for that container?

Does the disk mount now? Looks like xfs_repair didn't finish successfully, if it doesn't mount try running it again, also update to v6.12.10 before running.

There's nothing relevant logged, and the server still crashing in maintenance mode points more to a hardware issue, could just be overheating, or power related, since a rebuild will use more power/cause more heat. Reformatting the emulated drives will delete all data there, and IMHO nlikely that the disks are the problem, I would check CPU temps and/or try again with a different PSU, if available.

Check filesystem on disk4, run it without -n, and if it asks for it use -L

Yes, and my suggestion was to try the above to see if the issue returns or not, or wss this a one time thing?

I would recommend resetting the current stats and monitoring the pool for future issues, since it can be much harder to resolve a problem if a bad or dropped device goes undetected for some time.

Please post the diagnostics.

More zfs related crashes, I would recommend backing up and re-formatting the zfs pool.

If you really need Wi-Fi why not use an AP with client mode?

I would recommend updating, it's not complicated: https://forums.unraid.net/topic/97870-how-to-upgrade-an-lsi-hba-firmware-using-unraid/

You should delete those files if possible, though don't know if it will affect Plex.

Look in syslog for a list of corrupt file(s), those should be deleted/restored from a backup, then re-run a scrub to confirm there aren't any more errors.

That won't work, abort and run it again using the GUI, but without -n.

Try a different flash drive, just to test, no key needed, also look for a BIOS update.