Cable Modem Buying Guide

The following cable modem buying guide will help you decide which modem you should choose as your network device. Learn about various factors like ISP (internet service provider) compatibility, modem channel bonding, and the modems to avoid when selecting the correct cable modem for you.

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Choosing the Right Cable Modem in 3 Steps

Step 1: ISP Compatibility

First of all, you should consider ISP compatibility. When choosing the right cable modem, make sure your ISP has approved the modem for use on their network. Many people think any modem will work with their service provider. In most cases, this is not true, so use a certified modem (links to ISP approved modems listed below).


Astound Broadband powered by Grande

Astound Broadband powered by RCN

Astound Broadband powered by Wave

Blue Ridge


Charter Spectrum










Step 2: Speed Factor

Consider your internet speed. If your internet plan produces a 300 Mbps speed, an 8×4 channel modem (with a max theoretical speed of 343 Mbps or about 215 Mbps in actual speed) would not get you your full speed you are paying for with your ISP. However, a 16×4 channel modem (max theoretical speed of 686 Mbps or about 372 Mbps in actual speed) would allow you to achieve your full speed.

Keep in mind, some internet service providers will increase your speed for free for various reasons. DOCSIS 3.0 modems will eventually become end-of-life, so it is strongly recommended to purchase a DOCSIS 3.1 modem. Some ISPs have already moved to exclusive use of DOCSIS 3.1 devices.

Even if your modem is capable of a faster speed than your current internet plan (e.g. a DOCSIS 3.1 modem), future-proofing benefits you in time. Read more below about advertised modem speeds.

Step 3: Avoid Intel Puma Chipset Modems

Many cable modems include Intel Puma 6 chipsets that have known issues with network latency and network jitter. You may read more about the issues on the Intel Puma 6 chipset defects page, which also contains the full bad modems list (the do not buy list). To indicate a bad modem, will mark an Intel Puma chipset modem with a ♦ symbol.

Things You Should Know About Cable Modems

Why Buy Your Own Cable Modem?

The first reason to purchase your own modem is to save money. ISPs may charge up to $15 a month to rent one of their old modems. Therefore, you can save up to $180 a year on rental fees. Of course, those rental fees will continue to increase every year as well.

After five years, you could save up to $900!

The second reason for buying your own device allows you to pick which features you want in your modem, as opposed to the ISP forcing a limited features modem on you. Therefore, you have control over the brand and specifications of the modem.

Inaccurate Advertised Speed Claims

Even though cable modem manufacturers state a certain speed on their modem packages, those speeds are usually unobtainable. For example, the NETGEAR CM400 modem states a speed on the package up to 340 Mbps. However, ISPs will limit this speed for various reasons. Comcast states the CM400 will actually reach speeds up to 215 Mbps on their network.

The speed you get will only be a certain percentage of the stated package specification. Why is that? Various factors like the type of server, total number of users on the network, computer equipment, services offered by the internet provider, and other factors will throttle the full output of your modem speed.

Keep in mind that the stated data rate (download and upload speed) is just a maximum theoretical number.

Even DOCSIS 3.1 modems may advertise speeds of 6 or 10 Gbps, however the ISPs will limit these cable modems to 2.5 Gbps or slower due to network capabilities.

Cable Modem Channel Bonding

When you see a modem with 16×4 channel bonding, that means it has 16 channels for downloading and 4 channels for uploading.

The rule is simple – the more channels a modem has, the faster the data rates will be. So, a 16×4 channel modem achieves a faster data rate than an 8×4 channel modem.

In other words, the more data channels your modem has, the more speed the ISP can push to your home (if you have purchased the fastest speed tier from your ISP).

The chart below explains the speeds for each channel tier.

Channels (DOCSIS 3.0)Max Theoretical Speed
4×4172 Mbps
8×4343 Mbps
16×4686 Mbps
24×81 Gbps or 1000 Mbps
32×81.4 Gbps or 1400 Mbps
32×8 (DOCSIS 3.0 mode)
10 Gbps or 10,000 Mbps

ISPs use the data channels of the modem to deliver the internet to your home. The internet is like a highway and bottlenecks and slows during peak hours. However, having more lanes of traffic or data channels allows you to avoid congestion and keeps your full download speeds going.

DOCSIS 3.0 vs. DOCSIS 3.1

Data Over Cable Service Interface Specification (DOCSIS) allows for the transporting of data over a coaxial cable (internet service).

The most widely used format by cable internet providers remains DOCSIS 3.0. Most ISPs support DOCSIS 3.1, although some neighborhoods may have to wait years before DOCSIS 3.1 capability reaches them.

The main difference between DOCSIS 3.0 and 3.1 is the capable speeds. Comcast states that a DOCSIS 3.0 32×8 channel modem will reach actual speeds of about 935 Mbps on their network. While a DOCSIS 3.1 modem will achieve a speed of 1000 Mbps or 1 Gbps or faster. If you want speeds in excess of 1 Gbps (for future-proofing), you need a DOCSIS 3.1 modem.

DOCSIS 3.1 features backwards compatibility with a DOCSIS 3.0 network. So, if your ISP has not yet upgraded to DOCSIS 3.1, a DOCSIS 3.1 modem will still function on a DOCSIS 3.0 network.

Pros and Cons of Combo Modem and Router Devices

Many network devices classify as combo units. In other words, a cable modem and a WiFi router combined into one device. The list below contains the pros and cons of these devices.


  • Less clutter (one less power cable and one less device)
  • Less hassle to set up since there is only one device


  • If either the router or modem fails or becomes obsolete, you have to replace the entire device
  • Locked into the capabilities of a most likely limited WiFi router, as opposed to buying a separate, better WiFi router with more advanced features

Consequently, it is usually cheaper and easier to upgrade modems and routers separately.

Cable Modems vs. DSL Modems

DSL technology is older and slower. Most DSL providers are not in a hurry to upgrade their phone lines. If you have a choice of internet service providers, choose a cable internet company.  A few cable modems are capable of reaching speeds beyond 1000 Mbps (or 1 Gbps). DSL cannot compete with the ultra fast speeds of cable internet (or fiber internet).

Cable Modem Care

Modems require little care. The most important thing to remember is that cable modems can get really warm. Do not block the vents on the cable modem. Also, make sure you have enough ventilation circulating around the device.

Finally, do not leave modems near heat sources. Your modem should function properly without any other maintenance (other than occasionally dusting the device).

Cable modems come from several manufacturers, but the most popular ones are ARRIS, NETGEAR, and Motorola. If you are looking for a company to support your device for the next several years, those mentioned earlier are your best bets.

Warranties will range from one-year to two-years from the modem manufacturers. Cable modems rarely fail as long as they do not get too hot. Also, if you buy a new modem from Amazon, they will offer an inexpensive extended warranty (just a few dollars to add three or four-year coverage).

Brand New vs. Used Modems

Avoid purchasing a used modem. A pre-owned modem may not have been deactivated from the previous owner’s account, which will likely leave you with a worthless device. Plus, with a used modem, you have no idea of the condition of the equipment. The previous owners’ may have immersed it in liquids or encountered some other disastrous event with the modem; it could be a fire hazard! Always buy a new modem to avoid hassles.


To help you decide which cable modem to choose, please follow the three steps at the top of this page.

To summarize:

  1. ISP Compatibility
  2. Speed Factors
  3. Avoid Intel Puma Chipset Modems

With the many options for modems, reviewing your ISP approved modems page may help with deciding which modem is right for you. The best DOCSIS 3.1 cable modem today belongs to the ARRIS S33, which most major ISPs support.

ARRIS S33 Cable Modem Package
ARRIS S33 2.5 Gig DOCSIS 3.1 Cable Modem



44 thoughts on “Cable Modem Buying Guide”

  1. I am about to buy internet modem. What is the best wireless router? Docsis3.1 and channels 32down?
    That works with your RCN..
    Can you give me a list of companies and models so I can buy.

    Thanks a lot

  2. I want to hookup my own internet phone service (Huma). I have not seen modems listed that allow this except for Xfinity. Can you shed any light on this subject?

    • Did a Google search for Huma phone service – nothing popped up.

      Maybe you meant Ooma, which requires an Ooma device and a router (any will work), a modem, and an internet service provider (ISP). Ooma only provides phone service; they are not an internet service provider.

      So, for a normal setup, if you already have an ISP and a modem, you just need to add a router (which you may already own). Once you have any router, connect that to the Ooma device. You do not need a special modem or router for Ooma service.

      If you meant Ooma, here are some instructions to help setup the devices.

  3. I currently rent from xfinity My bill reads ” Internet/voice equipment rental ” if that tell u what I want to replace? the rental is 14.00 per month.What should I buy to replace it? Thanks. Jack

    • Hello John,

      Check out the XFINITY Approved Modems page. There are recommended modems depending on if you just need a cheap modem or WiFi or if you are going for the fastest speed available in your area (DOCSIS 3.1 modems). At the time of wiritng this, the NETGEAR CM400 on Amazon is only $30! That is only 2 months of rental fees.

      Definitely get rid of that rental fee. At $14 a month, that money could be put to better use.

      Stay safe, John.

  4. Hi there. I have a 200 mbps plan that somehow does not work well in a bedroom about 20 feet from the modem/router (currently Xfinity combination) when another device is in use in the main room. My place is small, but we may move into a bigger space, and also have completely embraced a lot of smart home technology. Looking to rid myself of internet issues, I am thinking of upgrading speeds with my ISP and definitely want to purchase my own separate modem and router. Is gig internet and DOCSIS 3.1 overkill? How long until 3.0 is obsolete or just not good enough anymore? And also when is a normal time to replace a router or modem – do they dependably last 5 or so years? Thanks!

    • Hello Matt,

      Gig internet and DOCSIS 3.1 is only overkill if you don’t plan on upgrading to that speed in a few years. DOCSIS 3.0 won’t be going away for several years due to the slow implementation of DOCSIS 3.1 in the USA region (most people don’t have access to DOCSIS 3.1 speeds).

      Keep in mind, faster speeds may not fix your WiFi issues due to building materials in your home or interference from other electronic devices. You could certainly try a faster speed, but just be mindful it may not fix your issue. Hard wire (connect an Ethernet cable) when you can. You should only need to replace a modem or router when you want faster speeds. These devices are really dependable since they have no moving parts. As long as they stay cool, your devices should give you a decade (or more) of dependability.

      Hope that helps you. Stay safe, Matt!

  5. I have Centurylink internet service & they say my modem is outdated. They suggest me getting another modem thru them & upgrading my internet speed but a family member suggested purchasing my own modem. Any suggestions??

  6. I just set my parents up with xfinity cable and internet package. They need to purchase a modem and router. I have looked over the approved list that xfinity provides. However, I am confused. Are the modem and router separate from each other, as in we need to purchase 2 different devices? The internet plan they have is only 100Mbps. The only devices they use are 2 cell phones and the smart tv. Can you suggest what to purchase for the lowest cost but sufficient enough to run what they need it to? Thank you!

    • If a modem is on the the approved modem list marked as having WiFi, it means the device is both a modem and router combined into one box.

      Based on what you asked for, the TP-Link Archer CR700 is the cheapest device. The CR700 contains a WiFi router and the device is capable of faster speeds than what you parents currently have, so if they ever get their speed upgraded, the CR700 will still be able to handle it.

      Hope that helps, Jennifer.

    • Al,

      First of all, i3 Broadband’s website is a horrible experience. It forces visitors to input a zip code to view any of their links (even the Terms of Service link at the bottom of the page). After inputting a zip code, here is the information they provide for modem and router use:

      “i3 Broadband provides the Optical Network Terminal (ONT) to provide your services in your home (Kinda what people think of as our “Fiber Modem”). And no, we do not charge any extra fees for it.

      Routers are what provide your WiFi (wireless coverage) in your home, and you may absolutely use your own router.

      Cable Modems, and Cable Modem/Router combination units are not compatible with i3 Broadband’s services.”

      So they don’t charge a fee for their modem equipment. You can use whatever WiFi router you like. Fiber services usually provide the necessary modem due to the specialized nature of fiber vs. cable internet. Hope that helps you, Al.

  7. Very informative article! Would love some advice.

    I’m updating my current Apple wifi system, with modem/router from Spectrum and 200Mbps of service to the Eero dual band mesh wifi w/speeds up to 500 Mbps and purchasing my own modem. I’m dropping the TV portion of services and just keeping internet, so just need a modem. I’m wondering if you have any suggestions on particular modems that would be best with this new set-up. Since I plan on streaming more content, I would like to keep the option of upgrading my speed open if necessary.

    The Arris SB6190 seemed to be a good fit, until I read it had the Puma chip. So compatible modems are: the Arris SB8200, Arris SB6183, and quite a few Netgear models. Would you recommend one brand over another? Is the SB6183 an older modem that I should stay away from? And, is there any benefit to the 3.1 at the lower speeds, assuming my ISP supports 3.1? Also, the compatibility list says SB8200 Rev4 and Rev6 – what do those references mean?

    Also, any feedback for the Eero system?

    Sincerely thanks!

    • Wendy,

      If you want to keep the option of upgrading speeds, you want a DOCSIS 3.1 modem so you can take advantage of 1 Gig speeds in the future. Spectrum only approves certain revisions of the ARRIS SB8200 to work on their network and you won’t know what you are getting when you order a SB8200, so stay away from that. The ARRIS SB6183 is not a DOCSIS 3.1 modem, but is a decent modem if you want a cheaper option. For feedback on the Eero Mesh WiFi, it is difficult to judge routers because every home has different building materials and unknown number of devices used by you and your neighbors (interference). Try it and if it doesn’t work well for you, you may need to purchase something else.

      Most ARRIS models contain the bad Intel Puma chipset (SB6190, for example). The NETGEAR CM1200 is a DOCSIS 3.1 modem as is the Motorola MB8600. The MB8600, however, is currently only rated for 400 Mbps speed service by Spectrum. Since it is a DOCSIS 3.1 modem, Spectrum should have this working for their 1 Gig speed tier in the future. Hope that helps you, Wendy.

  8. I currently have a Arris DG3270 (DOCSIS 3.0) modem/router for Suddenlink’s 1Gig service. It is really fast if I am on my docking station with ethernet to the box. However if I get a few feet away, in the same room), not to mention in another room) we loose signal. I have thought about purchasing a separate modem and router. Would a DOCSIS 3.1 be too much? Also we were thinking about having WiFi boosters about the house. Do you have any suggestions on those? Thanks.

    • First, the ARRIS DG3270 contains a bad Intel Puma chipset, so you will likely want get rid of that device. However, it sounds more like a WiFi issue for you. Suddenlink does not currently support DOCSIS 3.1 modems.

      You will likely want a better modem and since you have WiFi issues, you may want to go with a mesh WiFi system (uses satellites to extend your WiFi range). You can check out the best wireless routers if you go the buying a modem and router separately route. Visit the Suddenlink approved modems page to know which modems to avoid (do not buy Intel Puma chipset modems).

  9. In troubleshooting my latency, poor signal and very pitiful slow speed I used an unapproved wifi router. Keep in mind Spectrum kept pushing for me to upgrade my service. They said I had a lot of devices slowing it down.(at that time 7 cameras,2 4k tv and half the house smart)Which I told them who would upgrade when they can’t deliver the speed in the 1st place. (If any of you reading this have that kinda money to blow pass it my way)
    Anyways once I connected the unapproved wifi router my speed increased dramatically. By this time I had 16 security cameras,2 4k tvs,1hd tv the whole house is smart(outlets and switchs, lights and appliances) oh and I allow the guy next door to use it.
    Almost everything is wireless(i use 2.4 the 5g is only for the 2 4k tv’s since that’s all I have that will work with it)
    So why does the cable companies need to “authorize” our equipment.

    • WiFi routers don’t need to be “authorized”. Any router will work. Modems on the other hand, are limited to the ones certified for use on an ISP’s network. Testing is done to be sure a modem will deliver the speeds that are expected from the device and to be sure the ISP can deliver firmware upgrades to the numerous devices. That is why most ISPs limit the number of modems they approve so it lightens their workload.

  10. We have sparklight with a phone line so was looking at the NETGEAR CM1150V but it’s not on the approved list with sparklight any thoughts on avoiding an arris modem so we can keep the house phone I have to have it for work, thanks for the help in advance.

    • Unfortunately, the NETGEAR CM1150V is only approved for Comcast services. If you want phone service you are stuck with only the ARRIS options (for phone service to work properly with Sparklight, you must lease a modem directly from them). You can avoid using Sparklight’s phone service by using an Ooma device or something similar. It may be an option for you, Robert O. Then, you wouldn’t need a specialized phone modem since the Ooma device will handle calls; you can just use a regular modem for internet service.

  11. Hi Modem Gurus,

    Awesome site, has answered a lot of questions that other sites haven’t. I’m currently on Spectrum’s 200 Mbps plan with an Arris SB6141 that I picked up in 2016 when we had 100 Mbps service. Is there anything to be gained by picking up a 32×8 modem over the current 8×4 with our modest service plan?

    • Thanks, Marc, for appreciating the site! Short answer: you will have less congestion to deal with on a higher-channel modem. For a better explanation, check out Reddit user Fendral84’s post on the technical, but easy-to-follow answer.

      Marc, if you do update your modem, be sure it is a DOCSIS 3.1 modem. In the next few years, ISPs will be phasing out DOCSIS 3.0 modems. Mediacom already made this move in November 2020.

  12. I am considering buying my own modem router combo and eliminating the XFINITY rental fee of $14 dollars a month. My internet speed test is 305.1 Mbps with the ARRIS TG1682G. Thinking about buying the ARRIS Surfboard SVG2482AC it’s a 24 downstream x 8 upstream DOCSIS 3.0 cable modem. Can you advise me on how this device compares to what I currently have and if it will continue to be a reliable device moving forward.

    • Rick stay away from the ARRIS SVG2482AC; it contains the defective Intel Puma chipset. Your ARRIS TG1682 also contains the bad chipset, so maybe you won’t encounter any problems, but there is no sense in taking that risk when buying a new device. Rick you should go with either a Motorola MT7711 (supports speeds up to 600 Mbps) or the NETGEAR CM1150V (supports up to 2 Gig speeds for future-proofing).

  13. Quote from this page: if you buy a new modem from Amazon, they will offer an inexpensive extended warranty (just a few dollars to add three or four-year coverage).

    Is the extended warranty from Amazon worth the extra cash? Do you offer great support and really stand behind their warranty?

    • To be clear, the warranties are not offered by Amazon themselves, but a third-party company such as Asurion, LLC. You can read the reviews of the extended protection plans on a Amazon modem page to get an idea of what customers like or dislike about the plans (click the 3-Year Protection link, then click the number besides the stars to read reviews). Overall, probably not worth the additional cost as long as you are not using your modem as a football.

  14. After reading your input definitely going with 3.1 system but what does it mean “ modem with voice”? And should I be getting one with voice? I am going with Stratus IQ and will be getting speeds up to 500 download and 50 upload. They said I needed a modem at of at least 32 channels and DOCSIS of 3.0 or better. Also I renting their “pods” which I am assuming are their routers and extenders… Have you ever heard of this and should I buy my own as they don’t sell theirs they rent there’s 11.95 a month. They told me I could buy my own modem but recommended the pods?

    • Sherie, a modem with voice is a device you use if you need phone service. Most ISPs require a rented modem if you need phone service. There is a picture of their WiFi pods here about half-way down the page. You can read about the benefits of the WiFi pods. If you are buying your own modem, you can buy your own WiFi router as well. Save on that rental fee each month instead of using StratusIQ’s devices.

  15. The last comment I see is dated September 2021 and I wonder what might have changed between then and now (Jan 2022). I currently have “Optimum 100” but it is long past time for an upgrade and probable cord cutting. My modem is Arris TM822G and my router is the Apple Extreme Base station (802.11ac) along with an AirPort Express extender. Apple no longer makes routers and it seems to me that with a purchase of a new modem, a new router might be in order. My TV is a Sony Bravia 4KHDR, Ultra HD; I do not do any gaming, just tv watching/streaming and internet use. In zip 06880 (SW CT) and have read comments about Netgear CM 1000 and 2000. Can you offer any advice re modem and router? Thanks so much for all the good info here and in advance for any help.

    • Luisa, you can see a list of possible modems for consideration on the Optimum approved modems list. Since you have slower internet speed, you may be looking into budget equipment. The NETGEAR CM500 combined with the TP-Link Archer A7 router is a good value setup. The NETGEAR CM2000 would be a better purchase than the CM1000, due to the CM1000 being limited to 1 Gig speeds; the CM2000 is capable of 2.5 Gig speeds. On the opposite extreme, if you are looking for an all-in-one solution with 2.5 Gig capable speeds and WiFi 6 capabilities, the NETGEAR CAX80 is the way to go. Keep in mind you could still use your Apple router until Apple stops updating the software for your device unless they have done that already.

      • Thank you very much. I am apt to upgrade my speed with Optimum so your recommendation for the Netgear CM 2000 is appreciated. And also good advice to keep the Apple router until I need to change. I wonder about an all in one option in case one component dies – then both the router and modem are toast in one fell swoop. But if you don’t think that is a problematic issue, I will look into it as well.

        • All-in-one devices are actually not recommended due to the need to replace the whole thing as opposed to utilizing individual components that can be upgraded separately as needed. Some people, however, prefer less hassle with setting up devices with all-in-one options. Luisa, it is your call on how you feel on ease of use vs. individual devices.

  16. I’ve always used combo units but am looking for advice to setting up Modem and possibly mesh system (in order to get wired connection to audio devices in another room from modem/router location).

    I have Xfinitiy sub 600mbps speed and it meets my needs.

    I’m eyeing the Moto MB8611 and Arris S33 due to their similar price (both currently $150). Which would you recommend and any recommendations on router/system to pair with in similar sub $200 price range?

    • TC, you can’t go wrong with either the ARRIS S33 or the Motorola MB8611. It really comes down to which one is cheaper at the time of purchase. From a branding standpoint, Motorola has the edge because they don’t use Intel Puma chipsets in their modems. ARRIS has struggled with many of their devices due to the defective chipset (note: the ARRIS S33 does not contain an Intel Puma chipset).

      You can review the Best Wireless Routers page for router ideas, but the Google Nest Mesh WiFi Router System is tops on many reviews. Depending on how many WiFi Points you need for your setup, you can purchase this system within the $200 price range.

    • Marnie, this depends on who your internet provider is at your household. Who provides your internet? Some providers will not allow you to use a phone modem unless you rent it.

  17. After reading your article, everything makes sense now. Need to replace an old Netgear modem/router. Realized purchasing them separately will most likely save me money in the long run. Looking into purchasing the Motorola MB8611, but I’m stumped. There’s an option for either 1Gbps Ethernet port or 2.5 Gbps. Will it make much of a difference is my internet speed is under 500 Mbps? Do I need to purchase different Ethernet cables to what we have now? Please help.

    • Kelly, you should only be seeing one Ethernet port on the Motorola MB8611 (one 2.5 Gig port). The Motorola MB8600 utilizes a 1 Gig Ethernet port. Your speed won’t change if you are at 500 Mbps. However, you will be future-proofing when your speed upgrades.

      Your current Ethernet cables will be fine, until you jump to 2.5 Gig, then you will need at least a Cat 6a Ethernet cable. Please refer to this Ethernet cable comparison table. Your current Ethernet cable will tell you on the side of the cord which version you are using.

      • You are correct! Thank you so much. Didn’t catch that on Amazon. They give you the different options under one listing. As far as a router, would the TP-link AC1750 be sufficient? Checked the best router article, and the link takes me to this one.


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