The github repo mentioned this wiki article for multiplayer performance tweaks. Did you run through this list and make the recommended changes?

https://satisfactory.wiki.gg/wiki/Multiplayer#Engine.ini

Zabbix
https://www.zabbix.com/

Netdata
https://www.netdata.cloud/

Nagios
https://www.nagios.org/

SeaTools is a long-standing, trusted tool for HDD testing. I always have a bootable drive with the SeaTools bootable image on me for diagnosing hard drives.

https://www.seagate.com/support/downloads/seatools/seatools-legacy-support/

Keep in mind that testing a failing drive will likely make a failing drive worse. For your use-case this is fine, but for anyone else looking to test drives, please create a backup image of the drive prior to testing.