Good but some problems – nPlayer Plus Review

I was looking for an app to stream even 4k live channels to my iPad from my Linux based reciever and also my media files in other devices through my local home network . No problem with streaming files from my Nas and my PC HDD but there are too many problems with streaming live TV channels ( upnp/dlna media server ) . By the way what « bad gateway 502 » means ?
Review by Nmoslemi on nPlayer Plus.