Movie freezes while playing

Apple tv 4th gen - movie streaming - freezes/ runs / freezes runs or stops - i recycled wifi but that does not fix the problem. Called Apple Support, no fix - they are to call me in a couple of hours - this freeze issue does not happen on "classic" movies just the epics like the hobbit or Harry Potter - I have broadband comcast with streaming power and air play from a later 2014 MBP - so what is causing the issue?