Modem compatibility list, updated October 2018

*Suddenlink told us that all DOCSIS 3.0 modems will work with the company's service. But you should call Suddenlink to verify compatibility before purchasing.

Why you should trust us

Before joining Wirecutter, Joel Santo Domingo tested and has written about PCs, networking products, and personal tech at PCMag and PC Magazine for more than 17 years. Prior to writing for a living, Joel was an IT tech and sysadmin for small, medium, and large companies.

Thorin Klosowski spent almost six years at Lifehacker writing about hardware, software, and every other facet of technology.

Who this is for

You should buy a cable modem if you're currently paying a fee to rent one from your ISP. Most ISPs charge $10 a month to rent a modem—that's $120 a year, every year, on top of what you're already paying for Internet access. (Altice and Spectrum include the modem-rental cost in their current Internet plans, but if you haven't changed your plan in a few years, you may still be paying a rental fee; give Altice or Spectrum a call to see what your current options are.) Unless you have gigabit-speed Internet, you can expect to pay around $60 to $90 for a modem, which means you'll save money in less than a year.

Many ISPs rent out modems that double as wireless routers, which means that if you replace your rental modem with one you bought, you may also need to buy a wireless router if you want Wi-Fi in your house (if you're not sure what the difference is between a router and a cable modem, we have a guide for that.) Our favorite Wi-Fi router currently sells for less than $200, but you can find a decent one for around $100. That puts your total up-front cost as low as $160, which means it pays for itself in a year and a half. Your modem and router should last you at least a few years if not more, so even if you go for the more expensive option, you'll still come out on top. ISP-supplied modem-router combos tend to have bare-minimum feature lists and poor Wi-Fi range, while standalone routers have added antennas for better coverage, more parental control settings, and other nice-to-have features like guest networks and VPN servers.

ISP Monthly modem-rental fees (as of September 2018) Comcast $11 Spectrum $10 or no charge Cox $10 Altice $10 or $5 or no charge Suddenlink $10 WOW $10 RCN $2 to $11, depending on your location

(Legacy plans from Optimum, Time Warner Cable, or Charter may include a modem-rental fee depending on who your ISP was before the merger. Most current Spectrum plans do not have a separate fee. Fees current as of September 28, 2018.)

Don't buy a cable modem if you're on DSL or fiber; those technologies use different standards and connectors. Verizon Fios lets you buy your own modem-router combo, but you have only a single choice, and it's identical to the equipment they rent to you.

Also don't buy one if you use your cable provider for telephone service: The models we cover here don't have phone ports. If you need one that does, check to see which "telephony" or eMTA modems your ISP supports, and if the company allows you to buy your own. Comcast Xfinity's webpage has a checkbox so you can determine which approved modems are voice/telephone enabled, and Cox has a list of approved modems that are compatible with their voice services. Cable One notes that it only supports a couple of Arris modems (including the one it leases to you) for voice service on its support site, while WOW only supports its leased WOW! Advanced Modem for voice. The telephony modems you can buy are also more expensive than regular cable modems.

When to replace your old modem

You should get a new modem if yours doesn't support DOCSIS 3.0, the most widespread iteration of the Data Over Cable Service Interface Specification, which governs how cable operators deliver high-speed cable Internet. If you've had your modem for four or five years, give the model name a quick Google search; you might still be using a modem that supports only DOCSIS 2.0, in which case it's time to upgrade. But if you already own a DOCSIS 3.0 cable modem that supports your Internet plan's top rates, don't buy a more powerful (and more expensive) cable modem for the sake of future-proofing.

The first two versions of DOCSIS used only one downstream channel (for downloading data) and one upstream channel (for uploading data). DOCSIS 3.0 allows modems to bond multiple channels into a single data stream, giving you 38 Mbps per channel. Since those channels can combine, you can theoretically get up to 606 Mbps with a 16-channel modem and up to 1.2 gigabit per second with a 32-channel modem.

A modem's maximum speed, as the manufacturer lists it, doesn't mean all that much. Most ISPs limit 16×4 modems to around 300 Mbps even though in theory they can hit 600-plus Mbps. Most currently available 24×8 or 32×8 modems max out at 600 Mbps or 1 Gbps, respectively. If you buy a 1 Gbps modem but pay for only 300 Mbps service, your download speeds are still limited to 300 Mbps. Unless you're on a very congested network with constant slowdowns, you likely won't notice a huge difference from added channels on slower speed tiers.

How we picked

Photo: Michael Hession

Nobody really reviews cable modems—it's difficult, because you can't know whether it's the modem or the ISP that's to blame for slower speeds—so the few reviews that exist aren't very scientific. We also don't have the capability to test multiple modems on multiple ISPs ourselves. But generally speaking, modems either work or don't.

Instead, we started our research by considering all the DOCSIS 3.0 and DOCSIS 3.1 modems that work on the nation's biggest ISPs—Comcast Xfinity, Spectrum, Cox, Optimum and Suddenlink (both owned by Altice), Cable One, RCN, and WOW—and then narrowed the field to modems compatible with the most popular plans on those ISPs. (Altice and RCN don't publish a list of approved modems, though, and with few exceptions wouldn't verify whether any of our picks would work with their services.)

Compatibility: ISP compatibility is the main factor in choosing a cable modem. A modem either works with your ISP or doesn't. The first thing to do is to check your ISP's approved-modem list—here's where to check for Comcast, Spectrum, Cox, Suddenlink, Cable One, and WOW (PDF). If you're lucky enough to live in an area where you can choose from multiple ISPs, the capability to bring your modem from one provider to another is a nice bonus.

ISP compatibility is the main factor in choosing a cable modem. A modem either works with your ISP or doesn't. The first thing to do is to check your ISP's approved-modem list—here's where to check for Comcast, Spectrum, Cox, Suddenlink, Cable One, and WOW (PDF). If you're lucky enough to live in an area where you can choose from multiple ISPs, the capability to bring your modem from one provider to another is a nice bonus. Channels: Channel bonding refers to the number of downstream (for downloading) and upstream (for uploading) channels your modem can access. Modem channels appear on the box as a number, such as 16×4, 24x8, or 32×8. With DOCSIS 3.0, the more channels your modem has, the faster the speed, provided your ISP supports those channels. This means that if the ISP offers only 16 downstream channels in your area, using a 24×8 modem won't improve performance. The right cable modem is the one with the right number of channels for your service tier. The average Internet speed in the US is around 64 Mbps, and the fastest cable tier most major ISPs offer is between 100 and 1,000 Mbps (aka gigabit). If you have service ranging from 100 to 300 Mbps, a 16×4 modem will be enough. If your Internet plan is over 300 Mbps, you need a 24×8 modem or better. Our top picks will work for any plan up to 600 Mbps. We don't recommend 8×4 or 4×4 modems, because ISPs are phasing out support for those older models, even on lower-speed plans.

Channel bonding refers to the number of downstream (for downloading) and upstream (for uploading) channels your modem can access. Modem channels appear on the box as a number, such as 16×4, 24x8, or 32×8. With DOCSIS 3.0, the more channels your modem has, the faster the speed, provided your ISP supports those channels. This means that if the ISP offers only 16 downstream channels in your area, using a 24×8 modem won't improve performance. The right cable modem is the one with the right number of channels for your service tier. The average Internet speed in the US is around 64 Mbps, and the fastest cable tier most major ISPs offer is between 100 and 1,000 Mbps (aka gigabit). If you have service ranging from 100 to 300 Mbps, a 16×4 modem will be enough. If your Internet plan is over 300 Mbps, you need a 24×8 modem or better. Our top picks will work for any plan up to 600 Mbps. We don't recommend 8×4 or 4×4 modems, because ISPs are phasing out support for those older models, even on lower-speed plans. Warranty: Most modems come with a one- or two-year limited warranty that covers any catastrophic failure. A warranty is useful, because a company will typically replace a modem if it stops working due to defects. Malfunctions are not a common occurrence with modems, but since purchasing your own means you don't get a warranty through your cable provider anymore, the warranty is good to have in case anything goes wrong.

Most modems come with a one- or two-year limited warranty that covers any catastrophic failure. A warranty is useful, because a company will typically replace a modem if it stops working due to defects. Malfunctions are not a common occurrence with modems, but since purchasing your own means you don't get a warranty through your cable provider anymore, the warranty is good to have in case anything goes wrong. Price: We found that you should expect to pay $60 to $80 for a DOCSIS 3.0 modem that works with most plans and has the features you need to get the highest speeds available to you. Modems capable of full gigabit speeds are a significantly pricier at $160 to $185.

We found that you should expect to pay $60 to $80 for a DOCSIS 3.0 modem that works with most plans and has the features you need to get the highest speeds available to you. Modems capable of full gigabit speeds are a significantly pricier at $160 to $185. Heat: Read the owner reviews for almost any modem, and someone will mention that the modem gets hot. Most manufacturers list the operating temperature on modems as up to 104 degrees Fahrenheit, which is pretty hot for any electronic device. To keep your modem from overheating, make sure the vents aren't covered up and it's in an open space. Modems might be a bit ugly, but that doesn't mean you should hide yours away in a drawer. We'll keep an eye out for reports of excessive heat-related problems with cable modems, and we will update our picks as needed.

After researching all the modems currently available, we landed on four contenders for 24×8 modems: the Motorola MB7621, Netgear CM600, Linksys CM3024, and TP-Link TC-7650. We also considered two popular DOCSIS 3.0 16×4 modems that were our previous top pick and runner-up, respectively, the Netgear CM500 and TP-Link TC-7620, as well as three established DOCSIS 3.1 models: the Arris SURFboard SB8200, Motorola MB8600, and Netgear CM1000.

Our pick: Netgear CM600

The Netgear CM600 is a reliable 24×8 DOCSIS 3.0 cable modem that works with all the major ISPs at the time of this writing. It is compatible with the most commonly offered speed plans from Comcast Xfinity (up to 400 Mbps), Spectrum (up to 300 Mbps), Cox (Ultimate plan), Suddenlink (up to 500 Mbps), and Cable One (up to 600 Mbps), as well as with WOW's 100 Mbps plan. The Netgear CM600's user manual (PDF) claims compatibility with Optimum, but if you have Optimum service, you should call your local Optimum customer support number to check before you buy any modem. And owners like it, too; Amazon reviews are consistently positive.

Like most of our picks, the CM600 has a single Ethernet port to connect to your router and a coaxial cable connector, but no port for a landline phone. Photo: Michael Hession

The CM600 is a DOCSIS 3.0 modem with 24 downstream channels and eight upstream channels. This is plenty for most Internet plans up to 600 Mbps, and many ISPs require a 24×8 modem for their top non-gigabit plans, such as Spectrum's 400 Mbps plan or Cox's Internet Ultimate plan. Even though DOCSIS 3.1 has begun rolling out, that standard is backward compatible, so all DOCSIS 3.0 modems will work with DOCSIS 3.1 service.

While the CM600 has solid support from every major ISP right now, double-checking your ISP's compatibility page before you purchase the modem is still a good idea. ISPs update their modem-compatibility lists often, and they occasionally drop support for a modem with little to no warning.

Flaws but not dealbreakers

While reviews suggest that the CM600 is a reliable modem, Netgear's included one-year warranty isn't great considering most other modems come with a two-year warranty. Modems tend to run pretty hot—the maximum operating temperature for the CM600 is 104 degrees Fahrenheit (PDF)—so there's always a possibility of something going wrong if, for example, you don't place yours in a well-ventilated area. That said, we think the popularity and the wide ISP support for the CM600, compared with our runner-up, outweigh its lackluster warranty.

Runner-up: Motorola MB7621

Photo: Michael Hession

The Motorola MB7621 is another highly regarded 24×8 DOCSIS 3.0 cable modem, which promises the same performance levels on the same speed tiers as the CM600. It is less expensive and has a longer two-year warranty compared with our pick, so it's a good choice if the CM600 is out of stock or if you want to save another month's modem lease fees.

On the downside, the MB7621 isn't quite as widely supported by some ISPs (Spectrum and WOW are notably absent. Since it's CableLabs-certified, there's every reason to believe that the MB7621 could work on these networks, it's just they're not officially confirmed to work.). As with all of our picks, checking in with your ISP's customer service department for compatibility is a good first step.

Budget pick: Netgear CM500

Photo: Kyle Fitzgerald

Our previous top pick, the Netgear CM500 is still a good choice for the budget-minded Internet user. It shares many of the same features as our top pick, including wide ISP approval, at a lower purchase price. The trade-off is that ISP support for the CM500 usually tops off at about 300 Mbps instead of the 600 Mbps the CM600 is capable of. It is compatible with Comcast Xfinity (up to 250 Mbps), Spectrum (up to 300 Mbps), Cox (Ultimate plan), Suddenlink (up to 500 Mbps), and Cable One (up to 300 Mbps), as well as with WOW's 100 Mbps plan. On the plus side, you will be fine for a while, because DOCSIS 3.1 is backwards-compatible with DOCSIS 3.0 modems. It's a great pick if you don't need your cable company's fastest plans, or if they are unavailable where you live.

Upgrade pick: Motorola MB8600

Photo: Michael Hession

If you already have a gigabit-speed cable Internet plan, or know your ISP offers one and lets you bring your own cable modem, the Motorola MB8600 is your best option. It's usually less expensive than its competition, it has certifications from Cable One, Cox, and Xfinity, and it has a two-year warranty. Because it's DOCSIS 3.1 certified and supports 32×8 DOCSIS 3.0 channels, it should work with other cable companies that have enabled Gigabit Ethernet on their networks, but as usual you should check with your individual provider. For example, RCN's website goes out of its way to say that the company isn't currently supporting the MB8600, but it also don't specify an approved alternative.

You shouldn't get the MB8600, or any other gigabit modem, unless you know your ISP supports it today. Until your ISP offers gigabit service in your area, you won't know if it'll roll out DOCSIS 3.0, DOCSIS 3.1, or fiber to your home. The MB8600 should work for the first two situations, but it will be useless if they install fiber. For more, check out our section about DOCSIS 3.1 and gigabit Internet.

The MB8600 has four Gigabit Ethernet ports on its back panel, which aren't, as you'd expect, connected to a built-in router or switch—they can't be used to connect wired Ethernet devices. The ports are hidden behind a yellow sticker to prevent confusion, but it's easy to pull it off for access. The four ports are a bit of future-proofing, as they can be turned on by your ISP for link/port aggregation if and when your ISP decides to support it, though no ISP or home router does. The ports can also be used to support two (or more) separate IP addresses from your ISP. However, this feature is only applicable if you need separate accounts in your home for business and personal or family use, coming in on the same physical coaxial cable. For example, if you already have two or more cable modems in your home, each servicing separate accounts. The MB8600 could consolidate these into a single box, but you'd still need separate routers for each network.

The MB8600 has extra Ethernet ports under that yellow sticker, but they aren't functional except in extremely specific circumstances. Photo: Michael Hession

DOCSIS 3.1 modems cost around twice as much as our main picks, which means they will take over a year to pay off assuming a modem rental fee of $10 a month. Don't buy one just for the sake of future-proofing, or if you use a slower plan—DOCSIS 3.1 networks will be compatible with our DOCSIS 3.0 picks, which means that older DOCSIS 3.0 modems will continue to work just fine, albeit at lower speeds, on newer DOCSIS 3.1 networks.

Setup and activation

Regardless of which modem you choose, you'll need to activate it once you get it. Each ISP has a different activation process, but you'll need to either call the company or visit a URL to activate your modem. Here's how to activate your new modem on Comcast, Spectrum, Cox, Suddenlink, and Cable One. You'll need to call WOW's customer service line to activate your modem with that ISP.

Modem compatibility list, updated October 2018

*Suddenlink told us that all DOCSIS 3.0 modems will work with the company's service, but you should call Suddenlink to verify compatibility before purchasing.

The competition

We considered the Linksys CM3024, but this 24×8 modem has a few strikes against it. It only has a one-year warranty and isn't explicitly included on many cable companies' approved modem lists. However, its most glaring drawback is that it uses the Intel Puma 6 chipset. We hesitate to recommend modems using this chipset, which The Register reports can cause latency issues (especially with online gaming). As of this writing Linksys has not released a firmware fix for the modem.

The TP-Link TC-7650 is a 24×8 modem with a competitive price and two-year warranty. However, it appears on far fewer approved modem lists than the Netgear CM600, and it doesn't have very many online reviews.

Our previous runner-up, the TP-Link TC-7620 may still be available online, but TP-Link recently informed us that the modem will be discontinued at the end of 2018, so we have to drop it from our recommended list. If you can buy it at a price that's the same or lower than our budget pick, the Netgear CM500, then pick one up, but stocks will likely not be replenished after the current run has shipped.

The Netgear CM1000 is a gigabit DOCSIS 3.1 modem that is a contender for our upgrade pick. It is more expensive and has a shorter warranty than the Motorola MB8200, but the CM1000 is a worthy alternative if the latter is unavailable. The CM1000 has only one Gigabit Ethernet port in the back, so you won't be able to use link/port aggregation on this modem in the future.

The Arris SB8200 is another widely available DOCSIS 3.1 modem with similar specs to the Netgear CM1000 and Motorola MB8600, but as mentioned above it has a premium price over the MB8600. It has a long two-year warranty, and two Ethernet ports in the back to support connecting two routers/computers with two separate IP addresses, or for link aggregation (you'll still need a compatible router).

The Arris SURFboard SB6190 and Netgear CM700 are the most widely supported options for plans that are faster than 300 Mbps but not DOCSIS 3.1. These 32×8 modems are significantly more expensive than the 16×4 modems and are overkill if you have a 600 Mbps or slower data plan. If you're already on a gigabit data tier, we'd recommend that you just go ahead and buy a DOCSIS 3.1 modem. They are compatible with 32×8 DOCSIS 3.0 networks, and you'll be all set if or when your ISP adopts DOCSIS 3.1. These particular modems also use the problematic Intel Puma 6 chipset, which can cause latency issues. While the modem makers have distributed updated firmware fixes to the ISPs, it is ultimately up to your cable company to support the modem.

In the chart above, we list which of our cable modem contenders work with which ISPs based on information from each ISP. (Optimum/Altice doesn't provide a list of compatible modems.) Where applicable, we also include the maximum speeds that each ISP supports. We didn't include modem-router combos, because we don't recommend them.

What about DOCSIS 3.1 and gigabit Internet?

DOCSIS 3.1, which our upgrade pick supports, is the next standard for Internet cable modems and ISPs. It promises speeds of up to 10 Gbps, increased download efficiency, and better queue management for large downloads. The people behind DOCSIS say that the improved technology of the 3.1 standard will lead to better stability even at slower speeds.

We spoke with Belal Hamzeh, vice president of wireless technologies at CableLabs, the company that came up with DOCSIS, and he pointed out that a big strength of DOCSIS 3.1 lies in the upgrade process: To introduce DOCSIS 3.1, an ISP doesn't need to upgrade its cable lines—only the hardware in its facilities. This means that more cable operators will be able to offer gigabit speeds over the next few years, and many already do. Cox aims to have DOCSIS 3.1 in 99 percent of its service area by the end of 2019, with over 94 percent coverage in areas like San Diego, and the regional provider Mediacom has already rolled it out in parts of Indiana. Nationally, Comcast began to deploy its speedier DOCSIS 3.1 Internet plans starting with 15 cities in 2017, with plans to reach all 39 states they service by the end of 2018. Charter has plans to extend DOCSIS 3.1 gigabit service to 50 million homes in the same time frame. WOW currently claims 95 percent coverage for its customers.

You'll need a DOCSIS 3.1 modem like our upgrade pick only if you're in one of those covered areas and you have a gigabit-speed Internet plan—they're expensive right now, and you won't see faster speeds unless you pay for one of those gigabit plans. If you are in one of those cities and want to subscribe to one of the proposed gigabit Internet plans, wait to purchase a modem until you have the plan so that you know it's compatible. DOCSIS 3.1 is backward-compatible, so if you have a DOCSIS 3.0 modem and don't plan on upgrading to gigabit speeds, the DOCSIS 3.0 modem will continue to work with your ISP.

Right now, gigabit speed is possible on 32×8 DOCSIS 3.0 modems, but we don't recommend buying them since they use the problematic Intel Puma 6 chipset, and it's hard to tell whether your ISP has rolled out the fix for the chipset's latency problems. Our DOCSIS 3.1 modem pickis 32×8 DOCSIS 3.0–compliant by specification, so get a DOCSIS 3.1 modem if you want true gigabit speeds on any cable network. Cable One is the only major ISP that widely supports gigabit speeds over DOCSIS 3.0, although Suddenlink is expanding, with around 40 areas as of late 2018. Gigabit DOCSIS 3.0 is also available in a few cities from regional cable carriers, but it's not common.

Note that some DOCSIS 3.1 modems advertise "up to 6 Gbps" speeds. This is the theoretical limit of the DOCSIS 3.1 standard, and they are currently unreachable. In order to do so, you would need a business-class router with WAN port aggregation to enable speeds above 1 Gbps, and for now, most ISPs list 1 Gbps as their top speed tier for residential customers.

Gigabit fiber Internet plans are growing more popular, too—Optimum and Suddenlink's parent company, Altice, will be skipping DOCSIS 3.1 completely in favor of fiber. Fiber is generally faster than cable, especially in upload speeds, but it involves added cost for companies because it requires new cables and network architecture. That installation cost is at least partially why Google Fiber dialed back plans for its broadband rollout. Not to worry though—other providers, including AT&T Fiber, CenturyLink, Frontier, Verizon, and Windstream, are expanding their networks. Those who are looking far into the future (relatively speaking) are starting to get excited about 5G wireless Internet to the home and for mobile use. 5G uses fiber as its backbone, but uses wireless technology to deliver the service to homes and businesses.

As mentioned above, you shouldn't buy a DOCSIS 3.1 modem right now if DOCSIS 3.1 service isn't available in your area. Future-proofing is good in theory but difficult in practice. It might sound smart to buy the best modem available, but the interplay between the technology, your location, and the ISP means your chances of wasting money on a device that might not work in the future are higher with modems than with other types of electronics. Internet providers tend to be coy with their technology and service rollouts, so it's difficult to tell when—or if—you'll see a bump in the speeds they offer. For example, just because some parts of Denver have access to gigabit speeds doesn't mean the surrounding suburbs will.

Patrick Austin and David Murphy contributed to previous versions of this article.

This guide may have been updated by Wirecutter. To see the current recommendation, please go here.

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