Hey @evil_josh, sorry to hear that you're experiencing this 😞
Would recommend raising this with our TV & Content team here so that we can follow up with you and discuss it a bit further.
@AlexRH I doubt raising this issue will achieve anything - it has been over 3 years since the first complaint was made in this thread - additioanlly, Fetch still only provide 2ch audio for live streaming - no 5.1ch - astonishing really in 2018.
Optus generally is unable to provide support for hardware not supplied by Optus.
You may get assistance by contacting Yamaha?
Let us know how you go.