My iphone,iPad app stopes when playing music.

Hi
I have recently updated both my i phones,i Pads to latest apple OS version and each time i play my music it stops around 130 seconds and it goes back to the begins of the song.
Im using QNAP NAS with a Plex Version V0.9.14.6.
Can anyone help me with this as i have everything in there that i use. It was working just fine before that.