Stands to reason if there is no longer a cable running from your cable box to the TV, you will lose cable on the TV.  You need to connect another HDMI cable from the cable box to one of the non-ARC HDMI inputs on the TV, then switch to that input to watch TV.  

I’d probably use the HDMI cable that comes in the Beam’s box to connect the Beam to your TV, and leave the HDMI cable  from your cable box to the TV where it was originally. 

Thanks, JGatie. I think that's what I’ll do. Do you know what the plug in the middle of the other two inputs on the Beam is for? Is that to connect to a stereo system of something?

 Thanks again.

Thanks, Airgetiam. The only problem with that is that there is only room for one HDMI cable on my cable TV box. I think JG’s idea probably is probably the way to go. But I don’t quite understand why this isn't all made more explicit by Sonos during their set up procedure...

The manual:

https://www.sonos.com/support/en-us/sonos-user-guide/index.html#t=sonos-user-guide%2Fbeam%2Fbeam.htm%23TOC_Connector_panel5bc-2

You only need one HDMI on the cable box. It goes to the TV.

The TV HDMI-ARC port connects to the Beam.

I don’t quite understand why this isn't all made more explicit by Sonos during their set up procedure…

It really is pretty simple ...

The TV gets video and audio from sources (Fire TV, cable box) that are connected via HDMI inputs.  Then the Beam gets the audio output from the TV via HDMI-ARC (Audio Return Channel).  Without all these connections, you will be missing something. 

Ah it’s the ethernet cable.

It really is pretty simple …

 Sure, once you know what to do. But I shouldn’t have to ask others, or figure it out myself. They should know that a lot of people will already be using the Arc HDMI port for something and will assume (like me) that it’s the only one which can be used for whatever it’s already being used for. My life doesn’t ordinarily revolve around gadgets...

Not to make fun of you, but if your TV has an HDMI-ARC and between one and three other HDMI-ports, is it so hard to figure out that you have to put the HDMI-cable from your set top box in one of the other HDMI-ports once you’ve connected the Beam to the HDMI-ARC?

Actually I had noticed the third HDMI port shortly after opening this topic. btw: it would take two others beside the ARC since my Fire TV uses port #2.

 Not to make fun of you, but you might be surprised by how many people who grew up when television was still a rarity in American households, have no idea what “HDMI” is even referring to. Personally I feel truly sorry for the younger generations who have let technology take over so much of their lives, which these snarky, petty, disrespectful comments, that flow so naturally from them, are such an unfortunate byproduct.

  You might want consider not initiating conversation with the assumption that there is something wrong with a product when you have no knowledge of how the technology works.  You welcomed snarky comments with your initial attitude.  There is nothing wrong with not knowing how things work, but there’s no need to blame Sonos or anyone else  for your lack of knowledge of the basics.  

Sonos shouldn’t be responsible for knowing and telling you what your TV and cable box are capable of (there technically are some rare case where you can’t just plug your cable box to any HDMI port and get the same result...but very unlikely to apply to you) .  If you didn’t want to ask questions on the forum, then perhaps you should have consulted the user manual for your TV and/or cable box.

I did not mean to offend you. Just to clarify: I’m not very young (born in the sixties), so for example I remember my parents buying their first color TV.

Not expressly aimed at you, but on these forums I see at lot of people buying expensive electronics and not getting them to work properly. I am always amazed when people do not seem to be interested in how those expensive things work or in how to work them.

I read manuals (often before I buy things) and make myself familiar with the terms that are needed to use the things that I buy. Does that mean technology has taken over my life? No, it means quite the opposite: I use technology, but because I know enough about it, it does not rule me.

I very politely asked for assistance. There was absolutely nothing snarky about my question or the way I asked it. I figured out the problem myself before I received the obnoxious pile on, and for that I deeply regret my timing.

 And I hardly will waste my time with characters who consider  themselves “world-class superstars”, or “prodigies”,  no matter how facetiously.

I’ll find another way of getting support in the future.

Thanks so much. You all have contributed to making this country what it is today; a soul-less, narcisstic geekdom.

 God help us.

Your assumption that such titles are self given is incorrect.  The forum applies those titles automatically based on post count, questioned answered. and likes.  Indeed, you did not grant yourself the title of ‘Contributer I’.  Users have the option to turn the titles off, and honestly thought mine was already turned off.