Moving Music Library location

So I have ridiculously large music library - 638GB, 100k files, 10k folders, with everything tagged and sorted correctly. And yes that took a really long time. My old ReadyNAS NV decided to die after ten years of faithful service. Luckily I backed everything up. I bought a new NAS device (I love Synology now). So I went into the Admin application and tried update the library with a new path to the music library. The previous path was \oldnas\music\artists and now is it is
ewnas\music\artists.

The first time I did this, the plex server crashed. I restarted it. Tried it again. The library update timed out. But many of the artist had the trash icons over them even though the directory structure is a exactly the same.

How can I fix the timeout issue on the scan?

If you are not afraid of the command line, take your old database file and edit the references from the old to the new storage.