Stops playing for no reason

[peldc]

Playing a 1500 track playlist originally imported from iTunes, all missing songs synced over wifi.  Spotify randomly either stops playing or quits altogether.  I can get through a few dozen tracks, but I've never yet made it straight from A-Z, let alone have the playlist repeat at the end.  My tracks are alphabetized on my desktop, but don't appear that way on my devices.  They do play in alpha order, however.  Often Spotify will get through a series of songs and then pick up again at some random earlier point in the playlist.  (Don't even get me started about Shuffle.)  I'm gonna move to applemusic if I can't get this to work--just too frustrating to have to manually manage playback.  Any thoughts? 

[alus992]

I have new iPhone 6s 32 gb and Spotify app is constantly stops playing when I turn my screen of. I mean if that doesnt happen immidiately it will happen couple minutes later.

I have never had such problems on Android