Jellyfin
Jellyfin is a personal media streaming service. It is entirely open-source and free, unlike Plex.
I use it to have easy access to videos on my file server from any device.
It also offers the ability to play downloaded music, but in my case, I don’t use this feature as I prefer to listen to my collection with client-side players like MPD.
It is currently installed on a VM in the hypervisor server, with the media datasets mounted as shares.
No special configuration is required for basic use; just install it and add the desired paths from the Web interface.