I have an Xfinity X1 box running to my Samsung HW-K950 soundbar, and a Samsung JU6500 4K UHD Smart TV.
Whenever I try to watch a program through a streaming app (Netflix, Hulu, Prime Video, Youtube) I am able to watch 1 "episode" without any issues (can be a movie, 15 min, 30 min, etc.) Then, the audio stops on the app and on the cable. It's like the soundbar freezes and has to do a power-cycle to function again.
I've done a factory reset on 3 of the hardware components listed above but the problem persists.
I also have another X1 STB connected to an older Samsung surround system and a TCL TV in my bedroom and I don't have the same problem. This makes me think it is an issue with the HW-K950 soundbar, but I can't figure out what the issue is.
Have you updated the software on the soundbar? Please go to Settings>Support>Contact Samsung and provide the current software version on the television. How is everything connected?
TV software version: 1550
After some extensive trial and error, I think I've solved the problem. Changing the audio on the Netflix app from "original (5.1)" to "original" seems to have resolved the problem. I also had to change the audio setting in my STB from "expert mode" to "Dolby 5.1 auto-detect" to get the sound to work on the Hulu app.
HDMI from STB to Soundbar HDMI 1
HDMI from Soundbar out (TV-ARC) to TV HDMI 1
HDMI from Xbox One to Soundbar HDMI 2
HDMI from Nintendo Switch to TV HDMI 2
Attempting to use ARC from TV to Soundbar fails (No picture)
What's incredibly frustrating is that it seems Samsung and Xfinity are using incompatible audio coding to allow seamless interfacing between all 3 components (STB, Soundbar, TV).
I think if you check your network status under Settings->General->Network, you will see that your TV has disconnected from your Wifi. Samsung seems to be stonewalling on this issue. I tried all the BS fixes Samsung tech help suggested - forced DNS setting to 220.127.116.11, turned off instant start, and several other fixes numerous times with no success. I may have just solved the problem by plugging in one of my Xpods (Xfinity X1 wifi extenders) which has a hard wired Ethernet port built in, near my TV and running an Ethernet cable from the Xpod to the LAN port on my UN55MU6300 55-Inch 4K Ultra HD Smart LED TV. If you don't have any Xpods, but have an Ethernet port nearby - try running a cable instead of connecting through wifi.
I wasn't trying to run the sound through wi-fi to begin with; everything was connected via HDMI. The fixes I mentioned above worked and the issue has not returned. Seems like some incompatible sound codec between whatever handshake Comcast is sending and Samsung as it relates to apps like Netflix and Hulu. I probably won't buy anymore Samsung theatre equipment again. I shouldn't have to spend hours changing settings just to get things to work properly with one another. Too bad.