Need Help - Sound cuts off intermittently, Power On/Off issues

I recently purchased a Denon AVR x1600H and set up my 5.1 surround sound system. My TV (Samsung MU6300 series) is connected to my receiver - HDMI (ARC) port on TV to the HDMI Out port on the receiver. CEC is enabled on the TV. There are no other devices connected to the receiver

I am experiencing two issues:

1. While watching Netflix, Youtube, etc. on the TV, with the sound output as the receiver, the sound suddenly cuts off. When this happens, the TV continues to play video, and the receiver continues to be on, with no sound. Switching the receiver off changes the audio source to the TV speakers and the sound continues on the TV speakers. Switching the receiver back on ten minutes later switches the audio back to the receiver, and the sound is fine until this happens again
2. Switching the TV off switches the receiver off (HDMI Control is enabled), however, switching the TV on does not switch the receiver on. EDIT - during HDMI setup for the 'Universal Remote' on the TV, the switch on and off test works correctly

Wondering what I can do in this situation, could this be an issue with the HDMI cord?