Issue - Need help

Hi,
Hope I can post my request for help on this part of forum - I posted it on Android section a while ago and cant get any response - and it’s stopping me using Plex at moment:

Any help or advice on my problem would be great.

When trying to play music over my mobile (cell) phone network the android app i’m having a lot of problems. Songs will either just not start, or once started stop and I get a message “media player error” and the app stops

I have the latest version of plex on my nuc (updated last night)
I have latest version of android app (updated last night)
My phone is an old Samsung galaxy S3 - android version 4.3

The problem has been happening for about 7-10 days, both before and after the updates. Prior to this everything was working fine.

Strangely everything was working fine on my much newer phone - Sony z3 compact, which has a much more up to date version of android. Is it something to do with my android version on the Samsung.

Any help would be great
Many Thanks