"Access Denied" on one device but not another

Hi, all!  I have an S1 system with a Playbar and a Play:5 Gen1, I’m using the S1 Android app for control, and my music library is on an SMB share.

The app sees the devices and the music library and plays everything perfectly on the Playbar, but when I try to play a track on the Play:5 I get “Unable to play track-name - access to //computer/folder denied”.

I’ve tried the usual stuff -- deleting and adding the music library, power-cycling the devices, rebooting the router, switching from wireless to wired network connection.  I always get the same behavior.

It’s been a while since I used the Play:5 so I don’t know exactly when this behavior appeared.  Sometime in the last five months, though.

Any ideas for how I can go about debugging this?  Thanks!