Assuming you’ve read the error codes FAQ,  it may not be a problem for Sonos, but it may be a problem for your speaker’s connection to the Apple servers, due to wifi interference or some other networking issue, such as duplicate IP addresses. I’d certainly recommend the next time it happens, you submit a system diagnostic within 10 minutes of experiencing this problem, 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. 

Thanks.  

it may be an Apple issue but I have confirmed it is not a network issue (on ethernet, gave each device a dedicated ip, tried different speaker-including SONOS Amp).  I can immediately try and play a playlist with about 750 songs and it loads fine.  It is only when the playlist is more than about 1,500.  

I’ve been using AirPlay more often now to avoid the issue. Will also try and split some of the playlists in half.  

Haven’t trying dealing with SONOS support before.  If I have the time will give SONOS a call next time it happens. 

If that’s the case, my bet is a timeout from Apple’s servers in feeding Sonos the playlist data. But Sonos would be able to “see” that in the diagnostic data, whereas I’m just guessing.

There is a ten second timeout for loading playlists, if it takes longer then it will not load. This limit is in the app. I know for a fact that Spotify’s endpoint also enforces a ten second limit. I can’t speak to Apple’s.

I added support for huge playlists to the latest release of my Windows app, but telemetry indicates I have more work to do to make it 100% reliable.