I just bought a Q900 just 17 days ago and paired it with my existing N850 soundbar. Everything worked fine until I got home today and noticed the sound wasn't coming through the soundbar, I tried to switch the audio output to ARC as I've had to do a few times, but the option just wasn't there. I reset the TV, reset the soundbar, changed the HDMI, verified the input was digital in, unplugged and plugged in just about everything to check. Still nothing. I run my game console through the soundbar, the TV didn't recognize the soundbar but labeled the HDMI as the console and played both video and audio fine.
I called Samsung, they had me do literally everything I listed above again. They also refused to remote into the television because reasons, I guess.
I even went so far as to hook up a different Samsung soundbar that I own to the TV and still nothing, then I took the N850 to a different TV and the ARC works fine. It's a TV issue with this model it seems, and there is no information anywhere about how to fix it, other than getting a new one connect box all together.
Also, I am fully aware that I can connect to this soundbar via wifi, and that's how I have it for the time being. However, you cannot lie to me and claim that it is just as good as ARC because wifi doesn't support atmos which this TV and soundbar both do.
The only thing I can figure is that the ARC functionality just stopped working all together, or that an update messed it up. In any case, Samsung phone support is horrid, so I'm hopeful I can get better results this way.
Update: I have done literally nothing and it works again, I have no clue why. If you have a wifi capable soundbar, try leaving it on the wifi setting for a couple hours I guess?
I have a QN65Q90R, and let me say concerning the picture quality it is the best TV I've ever owned by far with accurate colors and plenty of shadow detail with no black crush unlike the "other brand" TV. Now for my issue: Everyone knows the built-in speakers in flat-panel TV's are subpar so I purchased a soundbar (no brand name is necessary as I understand this issue applies to all soundbars). I have a cable box plugged into the HDMI 1 port on the one connect box and I connected the soundbar to the HDMI 3 ARC port, then to the HDMI ARC output on the soundbar via a top quality HDMI high speed cable but nothing, the TV didn't recognize it. So I unplugged the power on the TV and soundbar including all the cables for a reset. Now by pure accident this time I connected the soundbar to the HDMI 3 ARC port on the one connect box first then gave it a try and it worked perfectly on Netflix and YouTube. I enjoyed my newfound sound for a few hours before deciding to watch network TV. Well as soon as I plugged the cable box into the HDMI 1 port the soundbar no longer worked and the HDMI 3 ARC port no longer recognized it and displayed 'UNKOWN' in my sources and dropped it as one of my Sound Output speaker options. One or the other would work, but not both at the same time. I tried everything, searched online and called the Geek Squad and the soundbar manufacturer but everyone and thing I read kept pointing to the TV. I thought surely not, but I called Samsung support to see if they could help. It didn't take 10 seconds and the (couteous) rep knew exactly what I was speaking of, explaining that others have called with the same issue. He openly informed me there is some kind of a gliche with the ARC on some new models and they are working on an update. So I'm left with using bluetooth or the digital audio cable, in which case neither can compete with the sound quality I heard through the ARC cable connection, or just returning a perfectly good soundbar to the store. I still have 12 days to decide, time will tell if I want to deal with this issue until whenever or if ever an update fix should come.