Try unplugging the Arc and TV from power for about a minute and disconnect your Arc from your TV. Then plug both back into power and redo the TV Setup process in the Sonos app. Don’t connect the Arc to the TV until the Sonos app instructs you to.

Our LG Nano 866 TV did something similar on Thursday. The TV had received a software update. I was able to get it all working again just by unplugging both the TV and the Arc for a minute or so as GuitarSuperstar has suggested above. But I didn’t need to do anything more. Once powered up again, it all sorted itself out.

It happened once before after another software update. On that occasion, the TV defaulted back to internal speaker setting and the eARC setting had been toggled to off.   

Thanks for the ideas.  I tried unplugging last night and again this morning, including unplugging the HDMI until it asks, with no luck.  

Just a thought, on the TV in the settings menu, under connection settings have you got the SIMPLINK option toggled to on?

Thanks for the note.  Yes, I have that checked.  I also went through the TV menu the manually set up the ‘sound bar’.  I tired setting it up with both Sonos and Philips as the manufacturer.  I did not have to set that up originally when I first set up the system a year ago and everything worked fine.  Not sure why it all stopped yesterday. 

I spent 2.5 hours on the phone with Sonos support yesterday.  They regurgitated the ideas and threads that you can find online and nothing worked.  They actually have old guidance and information related to LG TVs and spent probably an hour telling me the menu and settings selections for the TV were wrong.  They are now telling me that the problem is with my TV remote (which is working fine).  Sonos will not do anything until I go purchase a new TV remote to show that the problem happens with more than one remote.  I couldn’t believe that was the response.

Did you fix this issue or are you still living with it?
i have quite the same problem. 
unplugging and starting over solves the issue for a short time and then no response again. 
 

sonos customer service could’t help ‍♂️

The Sonos system will not work with the LG remote.  I am using a different remote for the volume right now.  Also, the Sonos system regularly stops transmitting volume from the TV.  If you change inputs, the volume will come back.  There is clearly an issue with the Sonos software or firmware (at least with my system) but they won’t help.  We are pretty frustrated.  When the system works, it is fantastic.

Why do you need the Magic remote setup on the Arc anyway when the LG TV will control the volume of the Arc using the HDMI-CEC Simplink connection, or are you using the Optical connection, or perhaps have some kind of middle-man device between the TV and Arc that’s interfering with CEC?

I don’t need my LG magic remote setup at all (although mine does work with my LG C9 TV), but that’s not important here, unless I have the TV switched off and still wish to adjust the Arc volume with the remote when playing music audio.

Hi everyone,

Given the HUGE amount of posts on here, and LG support pages, and REDDIT, and AVForums, etc... on the issues of interworking between ARC and LG TV’s I thought I’d post my own experience, which I hadn’t seen a similar answer for anywhere else…

To clarify, I am talking about LG TV (in my case OLED 55GX6) using ARC port (and eARC enabled) straight in to the HDMI port of the ARC, and specifically about the issue with loss of volume control from the Magic remote, and occasionally leading to loss of sound.

(NOT referring to the much promoted SONOS guide on working with the TV Optical out and ARC Optical to HDMI adapter and programming the Magic remote to use IR)

Having initially plugged this in and everything working a dream, and enjoying the Mandalorian in Dolby Atmos… Suddenly one day I started having issues. These started with volume controls failing, instead coming up with a “no entry” sign where the volume + or - were on the screen. And I noticed that the TV setup and Remote setup in the Sonos app failed mid-way through when I tried to remedy.

This was frustrating as I had my Magic remote for TV, also controlling my AppleTV on HDMI port 1, but had to then pick up my phone/Sonos app to adjust volume…

Following lots of googling and reading, I assumed the issue had been triggered by an auto software update or a power cut. I reset the TV, reset the ARC. Changed my very good own purchased cable for the Sonos ARC supplied one. Took both back to manufacturer settings. Checked for software updates. Tried turning Simplink off. Tried turning it on and going through the Universal Device Control menu to setup Sonos. Tried the same but using Phillips instead of Sonos (as recommended by Sonos). Tried all the above in various different orders. Nothing worked.

I unplugged the AppleTV, and tried all again, and actually managed to break the sound out from the ARC all together. When I chose “internal speaker” on LG, everything fine, when I went to ARC, nothing.

I was pulling my hair out.

Got Sonos support on the line. Following a full power cycle (about the 12th over two days….) and with their support, I finally got sound back. But hey ho, no volume control still.

I started to play with de-registering and re-registering the Magic remote, and at one point got the + and - volume controls back on screen… but they didn’t actually do anything. Pretty soon I was back to square one, ARC sound, but no volume control from Magic remote and failing TV setup and Remote setup in Sonos app.

But it was becoming clear the TV and the remote were talking. The TV was receiving instruction to adjust volume. But the TV wasn’t executing. So trying my best to ignore every single bit of Sonos advice out there re ARC and LG, which basically takes you down the Optical out and IR route, I started to focus on the fact that the TV needed to send the signal to the ARC over CEC. Remote to TV. TV to ARC. So the problem must be CEC TV to ARC.

I recalled that when on the chat to Sonos support, the engineer asked me to unplug the Apple TV that was in the LG TV HDMI 1, as sometimes some devices can create a CEC “storm” with the LG TV….

I had already unplugged my Apple TV some time ago, so knew that couldn’t be the issue. And I had no devices connected to the TV…. Or did I….

On the end of my HDMI 3 cable, I had an Apple Mac HDMI to USB-C adapter. You know the ones… white… take Macbook port to HDMI, power and standard USB. No Macbook was connected. No “device”. Just an adapter...

Unplugged it a hey presto….

Everything works wonderfully. Pretty much out the box. Unless you have a “device” (or adapter...) on another HDMI port causing a CEC storm…

Oh, and the TV setup in the app now works fine. But the Remote setup in Sonos app still won’t work. And shouldnt. Don’t bother with it, again, it seems to be relevant if you’re trying to use IR from Magic Remote.

So… hopefully this helps the huge amount of others out there fix their LG TV to ARC issues. (Not using Optical port!). Ensure you don’t have ANYTHING else plugged in to your LG TV HDMI ports, not even an adapter, and go from there.

Hopefully Sonos will work on updating FAQ’s etc to address the issues specifically to ARC/LG and CEC issues, not just the current Optical adapter focused ones.

@Glen Moose you sir are a genius! I’ve tried all the other crazy fixes under the sun, re-accepting licenses, wiping to default, etc.
 

Didn’t try unplugging an HDMI switch I’d added in! Did that, then had to turn off both the Arc and the LGGx for a minute, powered back on and hey presto the tv actually detected it as a Sonos which I don’t recall happening before (might be something new on the latest firmware or I never had it set up properly). The tv setup on the Sonos worked straight away as well  

I’ve plugged everything else back in and it seems to continue working, so might be something to do with the order in which everything is plugged in, as I power cycled stuff when I plugged the hdmi switch in. 
 

Now I’ve got to go re-configure everything as I wiped to factory default. 
 

This was a top tip, thanks very much!

I may have spoken too soon. Even without the hdmi switch the problem reoccurs. It’s not just hdmi cec that’s messed up, the tv stops detecting the Sonos on startup and switches to internal speaker and I have to switch it back every time. It also breaks earc as a 4K disc with true hd downgrades audio to DD5.1. This all started for me after the last firmware update from LG. Truly risible software from LG. 

@Glen Moose 

I had the same exact adapter plugged into hdmi 4 with nothing on the other end. All better now. I love you.

I was able to get our system fixed by unplugging HDMI cables using Glens recommendation above but alas, the problem is back.  I unplugged all cables from the TV but the remote will still not control the volume anymore.  Anyone else having issues recently?

Same issue here. LG OLED65c1AUP. Universal Remote says Sonos is set up, shows volume + and minus, but no actual change in volume in Sonos Arc. Sonos app says there is an issue with HDMI and if I go through the fix steps it guides me through, I get an error message that CEC is not on while it is on. 

Hey guys,

I have the same problems with my Sony A90j, the Arc works quite well for some time but suddenly the volume control stops working or the Arc won’t output any sound at all.

I experienced similar behaviour as @Glen Moose, HDMI adapters (not connected to PC) or even my PS4 (which wasn’t even connected to power) were still detected by the Sony TV as input sources.

After disconnecting the adapter and the PS4, the Arc resumed to work normally.

First i thought this was a problem with my Sony TV but after reading that you guys have the same problem with your LG TV, it might well be a Sonos CEC problem.

Nevertheless, this problem has to be fixed since it is not bearable to disconnect all HDMI input souces every few days/weeks when the Arc decides to not work again…

Same here

Ya..pretty ridiculous Arc connects setup like a champ.volume control on lg 2021 c1 magic remote controls volume on arc for a few min..then bam..gone..I see the volume symbols as well on tv..bit no control all of a sudden .Tried everything on the forum..etc... 

My apologies..I think it's an lg thing..my firestick remote will control the volume regardless of what i plug into hdmi..but magic remote will stop adjusting the volume once i plug my firestick in..weird

I started experiencing this problem yesterday. I see the + and - on the OSD, but the remote does nothing. I am able to control the volume using the Sonos app. 

And as if by magic, everything is working again. I did disconnect my PS4 when I turned on my LG tv. 

Same issue here on LG CX running 4:30:55 (and the previous two releases) - no control over volume or mute even though the screen shows that the remote is asking for changes.

I have an LG C9 + ARC in another room and that works just fine. When I power up the C9 I get a momentary green light on the ARC and it then all works fine. With the CX I do not get a green light on the ARC on power on - but I do get sound from the ARC - however there is no volume or mute control of the ARC - the screen shows that the remote is asking for changes but there are none. 

I have swapped the  ARC from the CX to the C9 (with the cable) and it all works fine…. there must be some compatibility issues (I have no other HDMI ports in use) -- any ideas ???

Update - decided to strip back the ARC by deleting the surrounds and power cycling it all with the ARC cable out…. and…. for now it works… have readded the surrounds and am getting ATMOS with volume control and mute. When I readded the ARC cable the TV showed that it auto detected a Sonos device so hoping this is the solution..

Had similar issues to others. After a power outage the set top remote and the magic remote wouldn’t change the volume on my Arc via the LG CX. You could see the +/- on the screen and even the mute but it didn’t control the volume on the Arc. 
 

Saw @Glen Moose suggestion about it being a cec “storm”. I cycled or unplugged all the devices on the HDMI inputs to my CX and it now works. Looks like the signalling caused issues with interference. In fairness the setup on the Sonos app did note there was some HDMI interference. 
 

Thanks @Glen Moose!

Oh my goodness, I was about to pull my hair out (the little I have left) with an issue similar to yours. After reading this, I noticed I had 2 unused HDMI cables plugged into my HDMI 3 and HDMI 4 ports, I unplugged them, tried adding my LG CX to my Beam Gen 2 in the Sonos app and it magically worked and I can now use my LG magic remote to control volume again. So dumb!