iTunes can no longer find music files after changing IP address of NAS

Solution 1:

As I can't comment on post so it comes as an answer:

Are your iTunes library accessing the NAS as a shared library or as imported files?

If it's imported files the "file location" stored in your iTunes library still contain the old IP. Changing all of these will take forever and I do not know if there is any application or plugin that can batch-change them. Deleting all files and importing them again might be the easiest solution to your problem.

You can see the songs location in the Get info -> Summary -> "Where:"

Solution 2:

1. Make sure you have rebooted the NAS since this change occurred.
2. Access the QNAP admin screen using your web browser.
   a. login with the admin account
   b. navigate to Applications->iTunes Server
   c. verify Enable iTunes server is checked
   d. set a new password for the iTunes server if you do not remember it
   e. click apply
   f. access the iTunes server using the link right above the password box, it should be http://192.168.1.200:3689 in your case
   g. check for any errors
   h. restart iTunes
   i. in the top left of iTunes, there is an icon with a Music note, if your iTunes server is running on your network, you should be able to select this drop down and change the server your iTunes client is accessing