Sonos is acting like a web browser: it wants to be the default sound output. 
 

I found a simple solution: I returned it to Costco.

Add me to the list.  New LG OLED CX with Sonos Arc/AirPod Pros.  Same issue as everybody else.  Had to unplug the HDMI cable so I don’t wake the wife up

Very surprising Sonos is having this issue for as much as I paid for my set up

this one:

https://www.amazon.com/BlueRigger-HDMI-CEC-Less-Adapter/dp/B07BFL8TM8

but this one is also advised as alternative:

https://www.amazon.com/Lindy-HDMI-Adapter-Female-41232/dp/B00DL48KVI

I have the exact same issue. Very disappointed with Sonos. They could at least clealry communicate on this issue...

Yeah same here. This is a ridiculous issue. My previous soundbar didn’t have this issue, and I am considering returning my Beam.

the solution is also not working in my C1, CEC is immediately turned back on automatically by the Beam.

any other solutions out there?

Hi all, How about this method of switching Bluetooth?

Try switching between both when using Bluetooth sound, it's just a few steps, so ease your mind.

Go to Advanced Settings > Connections
Click on Device Settings Configuration
- Turn off the simple link
- Remove sonos in universal control

   - Not used, but removed just in case

Reasons:

Turn off the convenience feature that sonos automatically activates

Go to Advanced Settings > Connections

Click on sound

- Turn off eARC in additional settings

Reasons:

Simple Link will not start automatically the next time the power is turned on.

I use Air pod pro with lg OLE48cx and tried it with beam(gen2),thanks.

Supplementation.
If you wish to return to the sonos soundbar, please reverse this procedure.
When ARC is selected, Simple Link is automatically turned on.
This is probably because there are frequent problems with no sound if it is left off, so it is necessary to turn on the path so that there are no problems with manual connection in any home.
I am Japanese and not affiliated with LG or Sonos, but I would like to try the IKEA rear speakers from now on.

regards.

I am amaized that 3+ years and sonos could not connect their own product to a tv and try to replicate this, to see the issue themselves? I had my same experience and i imagine others will continue to have it! All smart tv pwners will see how bad sonos products are due to this 1 bug! Unless they dont set up another audio output.

Hey, new to the forum. Recently purchased the Sonos Arc and ran into the same issue with my LG OLED C9 77 inch tv, with the HDMI Arc input being the only audio input I could play while using my sound bar unless I unplug the power cord or the HDMI cable. If I try using any other input it goes back to the HDMI Arc input immediately. One work around use could do is purchase an HDMI splitter. I listed the link below: 

https://www.amazon.com/dp/B079JQ9XXV/ref=cm_sw_r_other_apa_i_xM-XFbTJ3V16Z?_encoding=UTF8&psc=1

You'll be able to select the input you wanna use while leaving the HDMI cable in both the sound bar and tv as long as you select the splitter to the opposite input so it's not conflicting with your tv/sound bar. I hope this helps. 

Hi there - 

Also, a very simple solution I discovered: make sure eARC is turned on. Was having the same issue with my LG/Sonos ARC after I unplugged and restarted some things. I noticed eARC was turned off and when I turned it back on, it stopped switching from Bluetooth to Soundbar.
 

Steps on LG TV: All Settings > Sound > Additional Settings > Turn on eARC at the bottom.

Then Sound Out > Bluetooth.

Should stick. Hopefully works for you too!

Hello there. It’s funny that when I’ve read the thread and it was 3yo when started I was sure that by the end of the thread an anew solution would come oute.(maybe it’s like the build in Alexa they have and it’s like only for 5countries?

Overall their products are very good I have to say that!

I used to have 1 beam and 2 ones while now I bought a new tv (QNED 86inch 866).

I did what TD2014 said(as the latest solution but nothing happened ofc)

I am testing it with Airpods Pro2.

is there any solution this could fixed with Apple TV?(highly doubt it but HAD TO ASK)

I guess I won’t be able to watch movie or play PS while my newborn is sleeping.

I can live with that but would be so good if i could

I have a LG C2 TV with Arc bought last week, and the same problem here. I am not able to turn off the simplelink while my Arc is connected via eARC port, its automatically switch back on. Its only works when disable eArc function on the TV an after I was able to turn off the HDMi-CEC function. For me it’s a big disappointment.

LG suggestion was to have the Arc connected via Optical port and will have no problem but for me it’s just meh… Atmos is not supported via optical port, but if I keep the Arc I have to accept that I wont be able to use for example Bluetooth headphone or etc.. nonsense . Actually it is related just with Lg C2 and Arc so its model related within a brand...

My LG C9 TV works fine switching from Sonos to headphones/Optical/etc...

Just turn on eARC in additional settings

I did and it worked fine, but honestly for me its not the best “solution”. As you know eARC gives you better audio quality, and lets see an example: 

I use my headphone and if I would like to swith from headphones back to the soundbar its automatically turn on the simplink again, which means I have to do the same settings again if I would like to use my headphone ----- go to HDMI settings turn off simplink and after that, I will be able to change my audio output--- and it is so elaborate. Tried with LG soundbar and it is worked perfectly, nothing has had to be changed.

By the way thanks for your time and advice but I sent it back, that is not how it’s supposed to work. Nobody could say if this is an LG or Sonos software bug, because it is a bug 

It’s not a ‘bug’ per se, it’s the way CEC was written. Neither LG nor Sonos own CEC, they just use the specification as an implementation point. But since the CEC control (computer) is in the TV set, and the Sonos is merely a client to that, I’d start the discussion with LG. 

I found a solution for most streaming services at least :)

Won’t work for live TV though.

Buy a Roku, I have a Roku Ultra which is great when using the arc. All of the Rokus have the streaming services: Netflix, Disney, Apple TV etc.

Link your headphones to the Roku. When you want to use them switch them on,  and select. All done! Sonos  out of the frame

I am getting the same problem with a new LG OLED TV OLED77C2PSC.AAU and SONOS (Soundbar Beam Gen 2]).

If I turn OFF HDMI-CEC on the TV, The Sonos soundbar turns HDMI-CEC back ON within a few seconds.
So it is is impossible to switch to the Optical Output for headphones, …
(Other than disconnecting the HDMI ARC cable physically)

There is no setting on the SONOS app to disable Sonos automatically tuning HDMI-CEC ON.

Very annoying, Given this problem has NOT been resolved in the past 2-3 years, I will be returning my SONOS Soundbar and giving bad reviews wherever possible.

There appear to be NO response from SONOS support on this forum.

I am getting the same problem with a new LG OLED TV OLED77C2PSC.AAU and SONOS (Soundbar Beam Gen 2]).

If I turn OFF HDMI-CEC on the TV, The Sonos soundbar turns HDMI-CEC back ON within a few seconds.

I was able to fix this problem by setting geARC Support]=Off before setting nSIMPLINK (HDMI-CEC)]=Off

For Headphones
1. >...]->&Sound]->&Advanced Settings]->&eARC Support](at bottom)=Off
2. >...]->&General]->&Devices]->&HDMI Settings]->&SIMPLINK (HDMI-CEC)]="Off" (Will goto TV speaker)
3. Mute TV speaker
4. >...]->&General]->&Sound]->&Sound Out]->&Use Wired Speaker]="Optical Out Device"

For Soundbar
1. >...]->&Sound]->&Advanced Settings]->&eARC Support](at bottom)=Off
2. >...]->&General]->&Sound]->&Sound Out]->&Use Wired Speaker]="HDMI(ARC) Device"

Still far too complicated, compared to simply replacing the SONOS Soundbar with another vendors sound bar.

Has anybody tried an HDMI CEC-blocker in line with the EARC lead to the Sonos Arc? In theory it should stop the Arc switching the tv.

Hi folks, thanks for reaching out with the Sonos Community! I understand that we all want to keep the Sonos Arc/Beam and headphones connected to our TV at the same time and that kind of behavior is based on your TV on how the HDMI connections work because you are connecting two output devices to your TV. As others suggested this is more and can be handled appropriately by the TV manufacturers. You can try optical for better options but it will still up to you on how to proceed. Just let us know if you need anything. We and the community are always here to help.

Helpful

I can’t believe the Sonos Beam Gen 2 doesn’t have Bluetooth ability.  Wow, I just paid $500 for a soundbar that doesn’t even do what the cheap one it replaced did.  I was going to blast some Spotify tunes from my phone.  SO DISAPPOINTED!

Chucky999’s fix worked for me.  I was having same issue on a Samsung TV.  When swapping TV audio to Bluetooth headphones with a Beam connected to HDMI ARC, the Beam would hijack the connection back after about 2 secs.  Turning off HDMI CEC on the TV “fixed” the issue. However there should be a more elegant solution than this.  One “option” is to use the adapter with the Beam and go to the Optical output on the TV instead of HDMI ARC. The Beam won’t hijack audio when connected that way bu you loose some functionality like TV remote control of Beam volume.