iTunes attempts to mount SMB share using old SMB server name
iTunes is bloated and willful (my opinion), but here's a counter-point to that. I'm posting this as an "answer" in the fervent hope that someone will downvote it, tell me how stupid I am, and reveal (at long last) the "true" answer to the question, "Why does iTunes persist in looking for my media in the wrong place?". That said, here's all that can be done: 


Start iTunes, select iTunes, Preferences..., then the Advanced tab.  
Click the Change button, and in the dialog navigate to the location of your media.
Note that there are other options in the Advanced tab that will give iTunes greater autonomy over your file system than it already has. I've found them to be recipes for chaos, disaster and confusion, so I don't check them see this screenshot.


Finally, prepare to repeat this process frequently as long as you use iTunes. Frankly, the only reason I still use it at all is to a) store music on my phone, b) provide my playlists to Sonos. Again - hoping someone will strike me down, and we'll both be illuminated for it :)