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I recently moved into a home where each room has a coaxial wall plate. My ISP provides internet through a cable modem, where unfortunately the cable input is in a non-ideal location. Next to that cable input from my ISP, there is a wall plate where I could connect the coax cable.

If I did that, would I be able to connect my cable modem from another room's wall plate? How could I go about testing the connections?

I unfortunately don't have access to the original owners and can't find out how they did it.

  • 1
    Did you have a cable service installer as part of starting or moving your service to this location? They usually have the equipment to test installed cable. Assuming there is one cable with branches, you should be able to connect the incoming cable and put the modem at another outlet. Are you mostly interested in TV, internet or both? – Old Uncle Ho Aug 27 at 17:47
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    I had to install it myself, no cable installer as this ISP had been used previously. I am only interested in internet, other than this I have no use for the coaxial wall plates. – opius_pie Aug 27 at 21:42
  • why don't you simply run an internet speed test, then move the cable modem and do the speed test again – jsotola Aug 29 at 2:01
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Here's the caveat with old coaxial cable. If this is an older house, it might have cable already, but it's probably RG-59. This is from back in the days of analog signals, well before we were sending digital signals down them. If you have a satellite dish, you'll note they need RG-6 or better.

What's the difference? Shielding

Now, it's possible there's no interference on those old lines. In which case, stick your modem on and everything should be fine. Your modem should have a web interface and it should tell you the signal strength the modem is getting. Hook a computer to it and then hook the cable up. If you don't get enough signal, you might need to do some work (or call the cable company and have them do it for you, although they might charge you for that).

If you need more signal, here's some tips

  1. Find the main splitter. It might be in the attic, in the basement (if you have one), or is sometimes outside. All your coax will tie into it. With a multi-port setup they probably have a serial splitter. They should have labels saying things like -3.5dB. Your room might be connected to one that says something like -7dB. Make sure it's on one of the smallest dB loss ports. If not, replace it with either another multi-connector (one that has minimal loss) or just get a double-male and connect them together.
  2. Make a new run with better shielding. You should be able to find RG-6 readily, and probably RG-6 quad shield as well. This would eliminate a lot of signal loss back to the cable connection point. You can buy non-compression ends for this as well, if you don't want to invest in a coax end tool.
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    Thank you for the answer. Is there a risk if I plug my modem into the RG-59 cabling and the shielding prevents it from working? Is the only risk that it won't work? (don't want to ruin my modem or mess anything else up) – opius_pie Aug 27 at 21:47
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    It won't ruin the modem, you just don't want to plug it in and leave it either. They can burn up over time trying to work with the weaker signal, hence why I say log into the modem's console and check – Machavity Aug 27 at 22:09
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    And "burn up" is not necessarily like... set on fire, but a weaker signal triggers excessive signal re-processing that will damage the cable modem much faster than normal. – Nelson Aug 28 at 8:16
  • @Nelson that's probably the reason I had to replace my cable modem every 24-30 months for quite some time! After a couple of calls to the ISP about very slow performance they replaced the line to the house (squirrels, it seems like the insulation), and the guy ran a single new line to the jack in my office. I haven't had to replace a modem since. #TIL! Thanks!! – FreeMan Aug 28 at 15:23
  • That notion of wearing out faster because the signal is weaker sounds extremely dubious to me. – Reid Sep 4 at 4:16
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There's probably a gob of cable terminations in your basement or utility room. You'll need to find the two cables that go to the rooms involved (or simply place your modem there). With any luck they're labeled.

Using a pass-through splicer, connect those two. You should now have a continuous route between rooms, and the only question is whether the resistance and noise introduced by the splicer will substantially degrade your signal.

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    To add to this -- the easiest way to find out which cable is which (if not labelled) is to short the connector in the room, and then start measuring resistance from center to shell for each cable end in the basement octopus collection. If you don't have a volt-ohm meter, you can get one for very cheap at any hardware store; many of these come with a "continuity" setting that will beep if there's a connection. – Carl Witthoft Aug 27 at 18:22
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    @CarlWitthoft I don't follow - to short the connector I could just use a short wire/paperclip on the wall plate? And then use the volt-ohm meter from all the cables? – opius_pie Aug 27 at 21:53
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    @opius - that should work. Whatever type of cable you have it has basically two conductors, the center wire and the braided shell(s).connect them at the one end then test for that at the other end. If the shorted wire goes to a splitter before the other end that you want to test, then any cable coming out of the splitter would also be shorted. – Old Uncle Ho Aug 27 at 22:51
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    It's worth checking for existing shorts before shorting the cable in the room; if any are already shorted, discount them (e.g. mark with coloured tape) before you start. – Toby Speight Aug 29 at 8:36
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To elaborate further: You have a couple of options

  1. Plug modem in where it comes into house. (Probably not ideal due to location)
  2. Join outside cable to wall plate, then plug modem in in central utility room. (Again, might not be in central location.
  3. Plug modem in as in #1. Many modems have a built-in MOCA adapter (or you can buy one) and connect it to the wall plate. Join all coax connections in utility room via an N-way splitter, and set up another MOCA adapter and a wifi hub in another room.

FYI, I've done #3 -- works pretty well!

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