Try this:

Disconnect everything from the TV including the Beam. Make sure the TV and Beam have the latest firmware installed. Unplug the TV and Beam from power for a couple of minutes. Plug them both back in but keep them disconnected. Make sure you have Simplink (CEC) enabled in your TV settings. Run TV Setup under the Beam’s settings in the Sonos app. When the app instructs you, connect the Beam to the TV’s HDMI ARC port using the Sonos-supplied HDMI cable. When the Beam has been successfully connected to the TV, connect any other external media devices to your TV.

If this doesn’t work, repeat the same process above but use the optical adapter and connect to your TV’s optical audio port instead of the HDMI ARC port.

Thanks, I will try this tomorrow and get report back.

BTW, what I’m i missing out on by the beam not being connected via the app? Because the audio is still working fine.

@GuitarSuperstar Ok, I switched out to the supplied HDMI cable and the tv connected via the app and now shows in my tv inputs. I’ll keep an eye on it to see if it drops again.

If this has fixed it, though why would the change of HDMI cable matter? The one I used was 2.1 and brand new.

Thanks for any help.

From my experience in this community, the Sonos-supplied HDMI cable seems to be more reliable than other cables when using a Sonos device. This doesn’t mean that other HDMI 2.1 cables won’t work with Sonos. Most of them probably do, as long as they are not poorly made cables.

And the cable may actually have nothing to do with your issue. The act of unplugging the TV and Beam and redoing the setup process in a particular order may have been what finally allowed the Beam to detect the HDMI ARC port on the TV.

OK, I’ve tried everything. When I tried unplugging everything the soundbar connected as it should but then, a couple of minutes later, when I checked its connection had dropped, again. It’s not listed in the TV inputs and when i try and connect again via the app I get the same ‘ ‘HDMI Arc is not detected. Make sure the HDMI cable is connected to the ARC port and is turned on’ message.

The only thing that seems to keep the bar connected permanently is by using the supplied HDMI cable. So I’m not sure what’s going on. I can’t use this cable though as it’s too short for my setup.

Again, I am getting a surround signal so it’s not the end of the world but it is a bit strange.

The only other thing I have not tried, yet, is using the optical port. What do I lose using that as opposed to ARC?

Again, thanks for any help with this.

The main thing you will lose is the ability to control the TV using voice commands. But audio quality should remain the same with an optical connection.

@GuitarSuperstar 

DannyUFCfan,

Professional installers hate HDMI because this sort of experience is too common with all equipment. And the manufacturers always blame the other guy or claim “never seen this problem before”. 

There are a lot of moving parts to HDMI and manufacturers might interpret the specifications differently. As equipment is powered up and connected, the units negotiate with each other in an attempt to discover what features, such as surround sound. control, and picture quality, are supported by the other units. There are opportunities for glitches during this discovery process -- depending on the connection order and exact timing. After rebooting and trying again, the order and timing might accidentally be more favorable. A very difficult situation to deal with is disagreements between the units with respect to voltage levels and timing tolerances. It is possible that unit ‘A’ is at the low end, unit ‘B’ is at the low end, cable resistance is at the high end of the specs, and timing is on the edge. Voltage levels can vary slightly as the units warm up. This can cause failure a one point in time and success at other times. Investing in test equipment that can diagnose exactly what is wrong requires a few thousand dollars and some training.

It’s not a nice situation. Cable design quality varies and production control can be lax. Your best bet it to use HDMI cables that have been certified by a 3rd party. Unfortunately, these are not the cheapest cables. HDMI 2.1 cables are the best bet, but the threshold for being classified as “HDMI 2.1” is rather low. The cable supplied with the SONOS units work well in this application.

From your description I suspect that the voltage tolerances are ganging up against you and low cable quality pushes over the edge. One or both units might decide that the connection has broken or needs to be re-negotiated and, if you are on the edge, the negotiation may not be successful. This could be cyclic because the units will periodically check to see if re-negotiation is required.

Sometimes success is more likely if only the SONOS unit is connected to the TV as the SONOS unit is setup. Other units, such as Blu-ray players and cable boxes can be added later.