Not enough information to hone in on a great answer, I’d be certainly looking at questions such as which version of the Sonos software is in use, which NAS, and the possible potential of duplicate IP address issues interrupting the process of the Sonos devices processing the data on the NAS. I’d also be reading the wifi interference FAQ, and performing a simple network refresh by unplugging all Sonos devices from power, then rebooting the router. Once the router comes back up, you could plug back in the Sonos devices.

And, if none of that works, I would recommend that you submit a system diagnostic, and call Sonos Support to discuss it.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.

@Airgetlam, thanks for the suggestions and details. 

I’m having a likely related symptom - I can no longer add songs to playlists “unable to add...”.  Core functionality is still working.   

I would probably back up my playlists at this point in case something weird is going on. My iOS app can do this (see profile).

djlund999,

How many tracks and SONOS Playlists do you have?

@buzz , have ~ 17k songs and ~100 Sonos playlists. 

@controlav Got the app.  Is there a way to export more than one playlist at a time?

Sadly not, only one at a time.

So when you export one of the problem ones, does the export also have the reduced number of tracks?