allow me to extol the virtues of Onyx

[Fritz]

Onyx, if ya dunno, is a simple but useful utility that has saved much aggravation in my experience.

This am, for some reason, my media server wouldn't play nothin, music or video.
I use 2 different apps, Emby & JellyFin (which are forks of each other ... ish).
Long story why.
Neither would play anything.

I ran Disk 1st Aid on my dd boot drive, the boot drive on the networked server and the drives therein.  No change.

I ran Onyx on the networked server (MacPro3,1 on High Sierra).
Restarted, happy servers both.