Get this to happen and send in a diagnostic, then ask Sonos to look at it as they have troubleshooting tools we users don’t.
If you want to try poking about yourself you could look into the PC’s power management settings and make sure nothing in it is being put to sleep.
already checked the powersettings 
coz i learned that with the wifi long time ago :)
It ran through the exact same playlist all night yesterday without any glitches when i used the android app, so im fairly sure it must be the pc app that is glitching.
The ‘app’ used doesn’t do anything other than contact the application that runs on the computer in the speakers, and reflects what is happening. It’s merely a ‘remote control’. If you’re experiencing any differences, it’s more likely a difference in the ability of the device on the network to reach your speakers.
As suggested by @Stanley_4 , this would probably be traceable by Sonos if you were to submit a system diagnostic within 10 minutes of experiencing this problem, one from each controller, and call Sonos Support to discuss it.
you might be taking my meaning too literral, im not neccesarily implying there is a bug in the software itself. But something about how the software works on the pc is glitching.
for reasons, i had disabled the windows search service.
after enabling that and windows media player network sharing, i no longer have any issues, but i suspect its the windows search service that did the difference.
it seems reasonable to assume the software finds the file and points the sonos unit to it, but if it cant find the file it cant point the unit to it and that it utilizes the windows search service for this. Or something like that.
reinstalling the app and reconfiguring firewall didnt help, so its not a network connection issue.
going through my playlist for a second time, i do get “could not play” errors and it skips the track when im using the next button, but if i go and double click the track it will play, that is new. Going back and forth over the track with back and next buttons works afterwards too. This time the error is “could not locate the file”. Before no matter how many times i tried to replay a skipped track it wouldnt, but now i can go back to a skipped track and force it to play.
well bollocks…. cleared the playlist and made a new one and the problem returned in force .. almost all tracks were impossible to play.
clearing out my library watch folders i noticed they were added as network drives, gonna add as local drive and see if that doesnt work. going onto the netowork to find itself again might not be ideal. Funny how it was behaving so fine right after enabling windows search service.
woot how is that the best answer… jeezz.. the problem was that the library was a local drive added as a network drive + windows search was disabled. atleast those two things made things run more smoothly. The device reached the sonos unit just fine, when remote controlled with android app and ios app.
