Netgear Nighthawk M2 airplay distortion

Just did an update suggested by the router and after completion I cannot airplay to my Apple devices without digital distortion. Internet connection is fine but transmission of signal via airplay from iPhone to Apple TV will not work without distorting. If I connect everything to an extender network it airplays ok. Strange issue, any answers?
Model: MR2100|Mobiler Router Nighthawk M2