Songs will not play past a couple seconds when app is in the background or if phone is off.

[pantsball]

Plan

Free

Country

US

Operating System

iPhone 6

My Question or Issue

So, this has been going on for a while. I will play a song and leave my phone off while I do other things but maybe a minute or less after play, the app shuts down. I have cleared my background apps, reinstalled the app, and restarted my phone entirely multiple times and the problem persists. I just want to know what could be interfering with my music to be making it turn off like this. 

Possibly for more context, the iPhone is behind the most recent update, but the problem was there since before the update was released. (I also refuse to get the update because the iPhone system takes all my storage space.) 

Spotify is on version 8.5.49 

Please help, thank you.