Didn’t know where else to ask this so figured this would be the best place. What exactly is Coax used for? I ask because i’m self installing new Xfinity internet and the instructions say to plug in the Coax and what not. What exactly does that do? It that how the gateway actually gets internet or does it simply “distribute” the internet to other parts of the house?
Truly could not find a good answer on google so just wondering if it’s truly necessary or does simply plugging the gateway in work?
Mind you im not getting cable or anything like that. It’s simply wifi and that’s it. Thanks in advance.
Edit (Solved): To make things short, I plugged my Xfi gateway into these coax outlets in my house but they weren’t working. So, I tried plugging my Gateway directly into the main line outside and it works just fine meaning either the two ports I tried both happen to not work or the wires that take the connection to the rest of the house don’t work. So i’m gonna attempt to connect it in a port upstairs and see if it works just to confirm either possibility. But the problem is largely resolved. Thanks to the legends in the replies for the help!
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Coax is used to keep the signal in or to keep outside signals from interfering with it. High power signals are in coax to prevent cosite interference with other things that use signals. Low power signals, like those from antennas, use coax to keep other electrical noise from coupling with the signal and making it harder to detect and process.
In your case, the coax has a low power signal bringing the Internet to you and a low power signal back from you to Xfinity so that your data can get to the Internet.
/u/WRSaunders explained very well what it’s for. I’ll add to that a little.
The word “coax” is short for “co-axial”. The conductors run along the same axis. There’s a thinner one in the center (basically a wire) and it’s surrounded entirely by the other, which is basically a cylinder, with an insulator in between. This is what makes it good at avoiding interference.
Coax cables are typically used for radio-frequency (RF) signals. This is what allows cable TV or internet with a lot of information to work. The information modulates (changes) a high-frequency carrier which comes into a modulator/demodulator (modem), where it can be demodulated and sent on to a router or whatever.
If you don’t have the coax signal coming into your modem, then it has to get there some other way such as fiber.
Some houses also have coax running to various rooms. That was usually done to distribute TV signals (also RF) within the house.
Coax cable is a single conductor shielded cable. Because of this shielding, it’s a very reliable way to carry signals long distances. Without that shielding, over long distances there would be interference from other signals, like having to have a conversation across a loud bar.
Because it’s only a single conductor, it can carry one signal at a time, but thanks to the shielding and some other properties of the cable it can be a really fast signal. Imagine someone who talks like a really fast rapper or an auctioneer (“going once, going twice, sold to the man in the blue hat!”), and is loud enough to be heard across the bar, that’s what your modem does. It can send a many hundred megabit signal miles down the road to the cable company.
But the equipment to do that is fairly expensive, so for the home networking in your house we use a protocol called Ethernet or wifi. These are weaker signals so they don’t go as far. But the equipment to handle them is cheaper. It’s just like someone who can talk in a normal voice. Ethernet uses 4 pairs of wires, and they’re not shielded, so you can use a lower power signal and only have to go at 1/4th the speed for the same data rate.
So imagine that you’re at a table with your friends in the bar, and everyone can have a normal conversation deciding what drink to order. Then there’s a rapper/auctioneer sitting there who can yell everyone’s order all the way across the crowded bar to the bartender, really fast. That’s what your modem does, or to be more specific, your router is in charge of collecting everyone’s drink orders and giving them to the rapper/auctioneer (your modem) who then quickly yells them across the room.
It would be possible to connect all your devices with coax at your house, but the components to do it expensive. You can get a 1 gigabit Ethernet adapter for $15 but a 1 gigabit cable modem is $75.
Fiber is similar just taken to a further extreme – faster and more expensive per device, but even better performance than coax. And again, you could totally run fiber 6 feet from your desktop computer to your router, but it’s a waste of money when a Ethernet cable will perform just as well over such a distance.
If you don’t see a coax line going to your house somewhere from outside, you may have never had cable Internet before at that address so you need a technician. I’ve had an apartment where it was flat out cut at my wall.
Bonus, yes you can use coax in your house to distribute Internet too with Moca adapters and enabling it in the Xfinity router menu. It’s as good as Ethernet for the most part. I do this in my 70s split level.
Coax is the feed line that the cable/Internet signal is fed into and out of the house through.
There’s *usually* a demarc box outside your house, usually near your electric meter, that will have your service drop (service provider source line) and all the cable lines in your home, probably unlabeled. Your service drop will either be an aerial drop (line run through the air from pole to house) or underground drop (it’ll probably be an orange cable, buried underground until it reaches your house and then up the side into your demarc box)
If you have a multimeter and a scrap piece of coax, it’s pretty easy to find which outlet needs to be connected to your service drop. Either bend the center pin on one end so that it touches the metal fitting, or strip one end. Cut the outer jacket off, separate the metal mesh that you’ll find under that jacket from the foam core, strip the foam core from the center conductor, and twist the center conductor and metal mesh together to essentially create a shorted coaxial cable. Screw the other end of that cable into your coax outlet, then go outside with your multimeter to the demarc box and start testing outlets. Touch one probe to the center conductor and the other probe to the metal fitting (the part that screws onto the cable connections) and look for the outlet that reads 0/infinite ohms. Screw that outlet onto your ground block (double-sided female connector with a green ground wire running from it to your house ground/a clamp on your electric meter/cold water pipe, etc.)
Once that’s done, go inside and see if your modem is connecting to your cable provider and set up per instructions. If not, you’re disconnected at the pole or there’s an actual problem with one of your lines and you will need to call your cable company out to get your cable serviced.
It feels like these other answers are missing the mark.
Wired home internet works by creating a very long wire from the internet company all the way to your house. All the stuff from the company to the street corner outside your house we’ll call “the plant.” It’s mostly fiber optic, but converts to COAX for the last mile.
The COAX outlets in your house are connected to wires that run in your walls to a single splitter. Imagine a fork with long noodles coming out of the tines that end in those COAX outlets.
On the outside of your house, there’s a box with that splitter in it. When you get internet from a company, they simply come out and plug the handle of your fork into “the plant” to complete the long connection
It sounds like your splitter may not be connected to Xfinity for some reason, meaning all those outlets aren’t going to work until Xfinity comes out to check that and fix it. There’s just no way for them to know the condition of every house they serve. For that reason, when you’ve failed to self install, I know Xfinity normally does it for free.
Here’s a go at an ELI5 version for your use case:
The Coax connector is the “pipe” that allows internet water to flow in and out of your home. This pipe has special technology that lets water come in and water go out at the same time. It connects to the cable modem, which is sort of like an ice maker… you need water flow for your ice maker to work, so it can send those “packets” of solid water to your WiFi router.
Some cable companies provide an all in one device that includes a WiFi router and cable modem together, which sounds like may be your case.
So, yes, you 100% need the coax cable plugged in. The WiFi might work independently, but you won’t be able to reach anything in the outside world (only other devices connected to the router).
The Coax should be connected to Xfinity’s network (both cable and internet are transmitted over the coax cable)… that is how the gateway gets internet.
Check your basement or crawlspace to see if the outlets are hooked up to the coax line that runs from a near by telephone pole. Good chance that at some point a previous owner/tenet/isp ripped something out. Or that a splitted/adapter is corroded.
To give you better context on what you’re experiencing, I’ll explain a couple of things. I used to do cable work so I have some experience in what you’re dealing with. You identified the main coaxial feed to your property. From there, the coax cable will hit a splitter (at least one, it could branch into other splitters in other places in your house) and from those splitters, more coax will run through your house to each of the cable outlets. So if you imagine the signal coming from your neighbourhood tap to your house, to some splitters, to the outlet, you have an outlet that has an active signal. This would be considered an active or live outlet.
Now if you have a big house with say a cable outlet in every room, we don’t usually hook up every single outlet to the main line to your house, as every splitter drops the signal strength of the connection a little bit. If you have 8 outlets in your house but only plan on having an internet connection and maybe 2 or 3 tvs, I as your cable guy will identify the cable runs for the places you actually want service and hook them up to splitters and hook those up to the main line, so that only those outlets are active. That ensures that you will have good service.
You’ve hooked up the modem outside to the main feed to your house and proved that you have signal. The outlet you are trying to connect the modem to does not appear to have signal. That outlet is dead or inactive. What can you do? You can either go around your house trying to find an active cable outlet that is connected to your house’s feed, OR (and this is really what you should do) call Xfinity and tell them you tried to get your Self Install Kit (we call them SIKs) but it doesn’t work. They’ll them schedule a technician to come out and activate the line that you want activated (this was a very common task when I did this work, these jobs were known as “Failed SIKs” and were one of the easier jobs). Could you do this yourself? Maybe, but it’d be more convenient for you and better overall for your cabling if you have Xfinity come out and do it. Judging by how you described your cabling, if they are that old and unused, the technician will likely replace old corroded splitters and reterminate the coaxial ends and give you a better experience than you’ll get if you try to do it yourself.
To answer your original OP question: it’s how the internet comes from the outside world and gets into your house. All ISPs have to get internet to you one way or another. There are companies that do it through fiber optics, phone lines, 4g/5g connections, and Xfinity does it through coaxial cable.
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