If you’re using cable Internet, check your bill. You might be paying around $15/month “equipment rental” fee. If so, replacing the ISP-provided equipment with a cable modem of your own will eliminate that monthly cost.
Over time the saving will more than pay for the hardware you need to buy upfront.
Using your modem brings about other advantages, too. You then can pick a router, or a mesh system, with features and performance grades to your liking. And, in many cases, retailed hardware can improve connection speeds.
(Some of you might be happy with your ISP-supplied hardware and don’t mind paying the extra for the convenience and some potential added perks. That’s fine with me. But in that case, you should check out my take on how to get the best out of that gateway instead.)
This post will walk you through the process of replacing cable-provider-supplied equipment with your own. But first, let find out what a cable modem is.
Dong’s note: I originally published this post on February 15, 2018, and updated it on January 18, 2021, with substantial additional relevant information.
Cable modem explained: What is DOCSIS anyway?
A modem is a device that works both as a modulator and a demodulator. It converts service signals into computer data signals and vice versa. If the service is cable TV, then we have a cable modem.
Cable modems use the DOCSIS standard, which is an acronym for data over cable service interface specifications.
Extra: Cable Internet vs Fiber-optic
DOCSIS is a major contender of GPON, short for Gigabit passive optical networks, or Fiber-optic as we generally call it.
(Yes, there’s also the landline-phone-based digital subscriber line Internet or DSL, but it’s generally inferior in bandwidth and reliability. So, many DSL providers have been moving to GPON as the replacement.)
GPON is part of the fiber to the premises (FTTP), a.k.a fiber to the homes (FTTH), broadband delivery approach. Recently, it’s more often called PON since it can deliver Multi-Gig broadband.
The messy acronyms aside, Fiber-optic means you get fast Internet thanks to the fact that the optical data line runs (almost) directly from the provider to your home.
Indeed, this type of broadband delivers high speeds in both directions (upload and download). The downside is it’s expensive — new wiring required — and has a single point of failure. If a line is cut or broken, the Internet can be down for a large population.
On the other hand, DOCSIS is much more affordable since it uses the existing wiring for cable TV — the infrastructure is already there. It also works like a cobweb and, therefore, is resilient. When a cable breaks, that affects only a few families, if at all.
The biggest shortcoming of DOCSIS is that it has lopsided connection speeds — the upload tends to be less than one-tenth of the download. That’s the case with all cable connections, including mine.
With that, let’s continue with our main topic, the Cable modem.
Cable modem speeds: DOCSIS 3.0 vs DOCSIS 3.1
Currently, the world is using versions 3.0 and 3.1 of the DOCSIS standard. (So, there’s no need to worry about the earlier revisions.)
DOCSIS’s specifications can be very confusing. For one, it changes depending on the region. For example, the same modem specs might mean different speeds in the U.S. than they do in the E.U.
Also, it involves many technicalities, like channels, streams, QAM, and so on. I’m not getting into the details of all these in this post, nor should you care about them.
DOCSIS 3.0: Stream channels matter
In a simplified way, with DOCSIS 3.0, you can think of a cable modem’s speeds via the number of stream channels it can handle. There are downstream channels (for download) and upstream channels (for upload). More stream channels, or channels for short, translate into faster speeds.
Each modem comes with an indicator of the number of channels it can handle via two numbers. For example, the Netgear CM600 is a 24×8 modem. It has 24 downstream channels and 8 upstream channels.
In the U.S., the DOCSIS 3.0 standard delivers about 40Mbps per channel for download and 4Mbps for upload– these are ballpark numbers that vary from one provider to another. As a result, the CM600 caps at 960Mbps download and 32Mbps upload.
Generally, DOCSIS 3.0’s number of channels max out at 32×8. So a top-notch modem of this standard has cap speeds of some 1.3Gbps download. And that’s DOCSIS 3.0’s top bandwidth.
It’s important to note that just because a modem supports a certain performance grade (represented by the number of stream channels) doesn’t mean it will work at that grade. That depends on the service provider’s end (and the Internet plan you pay for).
And a provider generally loves to use as few channels as possible. The more stream channels, the more expensive equipment they need.
DOCSIS 3.1: Top-tier DOCSIS 3.0 is the base
And that brings us to DOCSIS 3.1. This standard delivers a higher speed per stream channel. This version needs fewer channels to deliver the same bandwidth and now has the cap of some 10Gbps in theory — that’s some 10x of version 3.0.
Though the actual speed varies from one vendor to another, a low-end DOCSIS 3.1 modem can generally deliver at least the same download speed as a top-tier 32×8 DOCSIS 3.0 counterpart.
The speed of DOCSIS 3.1 is so high that vendors now omit the stream channel numbers. Instead, they call the modem DOCSIS 3.1 and its cap speed, be it Gigabit or Multi-Gig. The Netgear CM2000, for example, is a DOCSIS 3.1 2.5Gbps modem.
In other words, the stream channel numbers, such as 32×8 or 24×8, are only relevant in DOCSIS 3.0, where most modems cannot deliver Gigabit Internet. Starting with 3.1, Gigabit is the minimum, and Multi-Gig is a new norm.
To sum up, DOCSIS 3.1 starts at the place where DOCSIS 3.0 maxes out. And generally, most, if not all, DOCSIS 3.1 modems can function as 32×8 DOCSIS 3.0 ones. But it’s ultimately the Internet provider that decides which modem works and at what speed.
(DOCSIS 3.1 includes other benefits, but they are generally irrelevant from the consumers’ end.)
Real-world cable (download) speeds
No matter how fast a cable modem’s advertised speed is, its actual ceiling speed is always its LAN port. This is the port you connect to a router’s WAN port.
That said, all cable modems with a Gigabit LAN port will cap at 1Gbps or lower.
Some modems can deliver Multi-Gig broadband speeds. In this case, they must have a Multi-Gig port (be it 2.5Gbps, 5Gbps, or 10Gbps) or features WAN Link Aggregation where you can combine two 1Gbps ports into a single 2Gbps WAN connection.
And, of course, to enjoy Multi-Gig broadband, you need to have a router supporting similar speed grades on the WAN side. After that, the speed must be available from the provider’s end. And, finally, you’re willing to pay for it.
The point is, there’s no need to get a modem that can deliver a faster speed than you pay for. However, it never hurts to have a top-tier modem if you want to upgrade your broadband later.
DOSIS3.0 vs DOCSIS 3.1: Which to get
In most cases, it doesn’t matter which you get if you have a sub-Gigabit cable Internet plan. However, keep in mind that if your broadband is slower than 300Mbps, it might require a DOCSIS 3.0 modem. So check with your provider.
On the other hand, with a Gig+ and Multi-Gig Internet plan, DOCSIS 3.1 is a must. On top of that, you might want to get a cable that supports Link Aggregation if that’s how your provider delivers Multi-Gig.
Here’s my simple rule to determine which type of modem to get based on your Internet download speed:
- 500Mbps or slower: Get a DOCSIS 3.0 modem.
- 500Mbps to sub-Gigabit: Either will do.
- Gigabit for faster (Gig+, Multi-Gig): DOCSIS 3.1
With that, let’s move on to how to replace that ISP-provided gateway with your own modem and be happier.
How to replace the ISP-Provided gateway with your own modem (and router)
This part is based on an Xfinity Internet plan, but the process is similar if you use any other residential cable Internet service, such as Time Warner Cable, Cox, Charter, and so on.
While this is about replacing an existing gateway, it also applies when you upgrade a modem or set up a new service. There are three steps.
A. Identify your current cable Internet’s modem/gateway
If you’re about to replace a provider’s equipment, there are two things to keep in mind.
First, are you currently using a modem or a gateway? Most users have a gateway instead of just a modem. If so, they will need a new Wi-Fi router in addition to a new modem, or they can get a retail gateway. A network needs a router — a gateway combines a modem and a router into a single box.
Second, do you also use phone service with your cable internet provider? If so, you will need a phone-capable modem/gateway, which is typically more expensive.
B. Equipment to get
There are many options for retail modems, routers, and gateways. You’ll need a set of a modem and a router, or a single gateway.
(If you also have a TV plan from your provider, the Internet modem has nothing to do with that. TV generally uses separate hardware.)
What cable modem to get
Modems are simple devices and tend to work similarly. The only difference between them is the reliability. The problem is to know that you have to use the modem for a long time to find out.
Extra: Dong’s recommended cable modems
So, it’s generally hard to review cable modems — it requires a lot of time. But below are a few I’ve personally had experience with over a (relatively) long period. Obviously, these are not the only options, but any will make a safe choice.
A. Best modem for a sub-Gigabit connection: The Netgear CM600
Netgear CM600 Cable Modem$94.99
B. Best modem for a Gigabit connection: The Motorola MB8600
Motorola MB8600 DOCSIS 3.1 Cable Modem$149.99
C. Best modem for a Multi-Gig connection: The Netgear CM2000
Netgear Nighthawk Multi-Gig Cable Modem CM2000$274.11
Generally, if you have a sub-Gigabit broadband connection, it really doesn’t matter what modem you get — be it a DOCSIS 3.0 or 3.1. Just make sure you get one that delivers the speed you pay for, and the provider supports you.
(Here’s the list of the approved modems and gateways for Comcast Xfinity. Note: You need to enter your home address or zip code or sign in with your account.)
The key here is to get what you need, it doesn’t hurt to get the fastest modem out there, but if you don’t have an internet plan that requires it, you’re just wasting your money.
Keep in mind that a phone-capable modem will work even when you do not have a phone service plan. So get one if you intend to add a phone service later.
By the way, an used or refurbished modem will work the same as a new one. Just make sure you get one that’s in good physical shape. Most importantly, make sure the device has been removed from the old owner’s account if you plan to use it with the same Internet provider. (You can check with the provider using the device’s MAC address.)
Once you’ve settled on a modem, it’s time to pick a router.
What’s the best Wi-Fi router or mesh system for cable Internet?
All routers, or mesh systems, work with any internet source. So if you get a good one, it’ll be good no matter who your provider is and what type of connection you have.
What’s also always true is the fact the router is the one that decides the performance of your home network. So, pick one that fits your needs and budget.
Or, you can follow the general direction:
- If you just need a reliable, able network and don’t want to spend too much? Get one of these Wi-Fi 5 routers. Yes, even today, Wi-Fi 5 is still relevant.
- If you’re ready for the latest and greatest, get one of these Wi-Fi 6 routers. For those living in a large home, a Wi-Fi system is definitely a must. In this case, also consider one of these Wi-Fi 6 mesh systems.
Or pick one of the following lists:
Retail gateways are available, too
An ideal setup is a cable modem and a router. However, if you don’t want more than one box at your internet drop, you can get a gateway (router/cable modem combo) of your own.
Keep in mind, though, that if you get a gateway, you’ll have to replace the entire thing when you want to upgrade your network, and not just the modem or the router portion of it.
On the other hand, if you have phone service, the ARRIS Surfboard SVG2482AC worked well in my experience. Again, a phone-capable gateway will work even when you do not have a phone service plan.
If you live in a large property and need a mesh-ready gateway, Netgear’s Orbi CBK40 or Netgear CBR750 are excellent options. They are available as single gateways or mesh systems. Neither supports phone service, however.
C. How to set up new cable Internet equipment
No matter what you get, be it a simple cable modem, a phone-capable modem, or a gateway, the setup process is the same. You need to activate your equipment on the provider’s network.
These steps, by the way, apply only to when you want to activate a residential Internet plan. If you have a business plan, you’ll likely need to call the provider.
Cable Internet setup: What you need
To activate a piece of new equipment, you need two things.
- A computer with a network port. If you have one of those laptops that only have Wi-Fi, get an Ethernet dongle for this job. Or, if you have an existing Wi-Fi router, you can use its Wi-Fi network — more on this below.
- Your cable account information (account number, phone number used when signed up, home address, etc.) or the login information. In my experience with Comcast, the Xfinity username and password are enough.
Steps to replace / install a cable Internet cable modem / gateway
These relatively specific steps apply to those with a Comcast Xfinity Internet plan. If you use a different provider, the process varies though it is likely similar.
1. Replace the old hardware
Remove the existing gateway or cable modem. (Make sure you return the equipment afterward to have the rental fee removed from your account.)
2. Connect the new hardware
This is an important part, and I’ll describe it in great detail to include different scenarios. In real life, it just takes a few minutes. Here goes:
a. Connect the service coaxial cable into your new cable modem or gateway securely.
b. Use a network cable and connect your computer to a LAN port of the cable modem (or gateway). If it has more than one port, you can use any of them.
A couple of things to note:
- Alternatively, if you get a new modem and have an existing router that has already been set up, you can connect the router’s WAN port to the modem, and then your computer to the router via its Wi-Fi or LAN port. Don’t do this if you have a brand-new router that’s not yet initialized. You can’t activate a modem using a router at its default factory settings. That’s because many routers require a live Internet connection (one with an already-activated modem) before you can set it up.
- Make sure your computer and router (or gateway) have the default (auto) DNS settings, meaning it will use the DNS servers of the Internet service provider. The good news is that’s always the case unless you have changed the DNS manually. Using customized DNS will cause the activation process to fail. So use the default one and you can change that later.
c. Now plug everything into power and wait for the equipment to boot up. Typically, this will take just about one minute, but you can give it a few minutes to make sure.
A bit of troubleshooting
Look at the lights on the cable modem (or gateway). You want to wait till the Online light (sometimes labeled as Signal or Sync or Data) is on solid.
The color of this light varies depending on the modem, but it tends to be white, blue, or green, and it almost always takes the symbol of a little globe. If this light doesn’t turn on, that means there’s no Internet signal. Check to make sure the coaxial cable is plugged in correctly, or call the provider.
Typically, you can now call the provider’s tech support. Give them the MAC address of the modem (or gateway) and get it activated that way. Or you can do that yourself.
Here are the steps for self-activation:
On your connected computer, launch a browser (such as Firefox or Chrome), you will automatically get to the activation page.
If not, try going to any website, and you’ll automatically reach that page. Or, if you use Comcast, navigate to this page: https://register.be.xfinity.com/activate.
Comcast might show a page suggesting that you download the Xfinity mobile app so you can finish the job on your phone. I’d recommend skip that and continue with the web browser. You’re really close — it’ll be a waste of time to download the app, sign in with it, etc.
In this case, choose to log in with your Comcast account and follow the onscreen instruction shown in the screenshots below.
If you don’t have an account or don’t remember the password, you can use the account number instead and go through a few other verification steps. After that, the new equipment will then be activated automatically and will restart itself.
The final step
And that’s it. Now your new equipment is ready. If you just activated a cable modem and have a new router, you can now plug the router’s WAN port into the modem’s LAN port and follow this guide to set up your home network.
Using your own modem, you have the option of replacing the router — and upgrade your home network — whenever you’d like. And when you do, note that you should restart the cable modem after you plug the new router into it for the two to work well with each other.