There is no “Sonos” codes that you should be using, the Denon ones are indeed the ones that would be used. Have you tried re-setting up the Sonos Beam with the remote? In settings, there’s definitely a process that you can use to re-train the system. 

On the other hand, if you’re using ARC to connect the Beam to the TV, the TV should be sending signals to the Beam for volume, rather than any IR from the remote to the Beam itself.  Does the remote work properly with the TV set?

And if you are indeed using an LG, why not use the LG commands for the TiVo remote, rather than the Denon ones? Or do you have a Denon that you’re also using the remote to control?

Thanks for your thoughtful reply. It is better than what I received when chatting with Sonos technical support.

I always expect a user to be more familiar than a phone rep. Much higher chance that a user isn’t working from a script, and at minimum wage. Those folks (and I’ve been one, too) are great for the 90% of issues, but don’t always have the knowledge to deal with the 10%. And there’s always the possibility that you get one who’s not really understood the training they’ve received. And, as simple as Sonos tries to make it, there are some complexities to their system. I’ve been a user for 10+ years, and still enjoy learning new things every day. 

Hopefully, this will help. Come back if it doesn’t. I’ll apologize, and come up with some other scenario. Or, another user will have a better answer.

Always more challenging to do this kind of thing when you’re not in front of the device, and don’t really know all the permutations that may have already been tried :) 

I’m having the same issue with no luck. I have a Tivo Bolt, using a TiVo remote to connect to our LG TV (no HDMI ARC). The Beam uses the optical adapter and plays well. But, when we moved homes, the Beam and TiVo remote don’t seem to talk to each other for sound. The Remote Setup process using IR doesn’t find the Beam when I try to replace the remote (it says an existing remote is connected to it, but it clearly isn’t). The Denon codes don’t work, but if there’s a specific one for the Beam, I’d welcome it. TiVo support forums said to go one by one through hundreds of unknown codes (give me a break and that doesn’t seem to work). Ideas welcome!! The TiVo remote works perfectly for all TV functions. 

I don’t know where Denon comes in your setup, but surely you need to use the LG TV codes to control volume to the beam? Also, it’s possible some update was sent to the tv that may have reset the sound out settings, so it’s worth checking them. 

Thanks for the suggestion. The LG TV codes wouldn’t do the trick. I did a hard reset and was able to get close. But, during set up, only the volume buttons were being read by the Beam and not the mute button. Very odd.