not playing the whole song

 I have that issue with some Qobuz songs.  The Qobuz app shows those tracks as Samples which do only play for 30 seconds.  Not sure what music source you were using when you had that same issue.

If it’s ‘all’ sources, there are two potential issues. The first is wifi interference , interrupting the connection of the Sonos device to the source. There is also, albeit less likely, a duplicate IP address issue, which can be ‘fixed’ by a simple network refresh. Unplug all Sonos devices from power, then reboot your router. Give the router a couple of minutes to come back up, then plug in your Sonos devices. 

That latter process will also pick up any DNS changes that are upstream, but those shouldn’t be periodic in loss of playback, they would be on/off.

It was either Pandora or Spotify. And it just happened when they did the recent update. It never happened before. Seems to have cleared itself up. But it happened for like three days. if it starts doing it again, I’ll unplug the speakers and restart my router. 

Sonos builds a small caché while playing tracks. This allows the system to play through common communication issues without interruption. If an extended communication issue depletes the caché, the player will mute rather than play trash. At this point the system makes a judgement call. If the communication issue seems brief, the mute will be extended, anticipating successful resumption. Unfortunately, if successful communication flip flops on the edge, the mute can be extended indefinitely or cause a stutter. If the communication issue seems hopeless, the system will abort the current track and start the next track.

We don’t have any control over the caché size. On occasion, just to be mean, I’ve disconnected the network and had the current track finish. This could be 20 or 30 seconds or more. As a result, it can be difficult to know exactly when an issue begins. A cat, dog, or kid could disrupt a network cable and be gone from the area before the music stops.

The SONOS diagnostics are very thorough and will log all of the network disruptions occurring in the background. Diagnostic detail sill begin to scroll out of view after approximately 10 minutes. My suggestion is for you to submit a diagnostic within 10 minutes of an event, then work with SONOS phone support. Here in the Community we don’t have access to the diagnostic data.