Rent No More: The Best Cable Modem To Own

Recently, Time Warner Cable joined the ranks of Comcast and Cox by charging $6 a month (up from $4) to lease one of their subpar (read: dated) cable modems. Here’s one way of getting around it, as noted in “How to Beat Time Warner’s Bullsh*t Modem Rental Fee.” (To be fair, Comcast and Cox have been charging subscribers a whopping $7 a month to lease cable modems for some time.)

Should you decide to buy a modem as a Time Warner customer, it’ll take 15 months to recoup the cost of buying a modem like the SB6141, and at the other two carriers it only takes 13 months—not to mention you can always sell the modem if you ever decide to for a few bucks.

Let’s assume you want the most future-proof cable modem currently available and that you’re subscribed to a fairly high-speed service plan. If those two variables are checked off, then the SB6141 is the right choice for you. Why? For starters, It’s approved for use with Comcast, Time Warner Cable and Cox. It earned 75% five-star reviews on Amazon and the lowest percentage of one-star reviews at 3.1.

In’s FAQ about which cable modem they’d recommend, their answer is officially this:

“I would have to update this question every week, so I won’t provide a list here. Let’s just say that Motorola Surfboard line seems to be the favorite among a lot of people right now.”

To back that up, the Comcast community on has been the most vocal about the topic and consistently recommended or concluded that one of Motorola’s Surfboard modems is the best in annual polls since 2004. And according to Jeff Heynen an analyst at Infonetics, a telecom market research firm, the 6141 is the most popular DOCSIS 3.0 cable modem in terms of units sold.

What’s Up, DOCSIS?

Before we get into the nitty gritty of why the 6141 is our pick, it’s worth getting the lowdown on what the heck this DOCSIS standard is all about. In a nutshell, Data Over Cable Service Interface Specifications standard has allowed traditional cable television operators the ability to deliver high-speed Internet service over their existing hybrid fiber-coaxial infrastructure.

To date there have been four versions as governed by CableLabs, a non-profit R&D consortium founded in 1988 by cable operators to oversee the certification of DOCSIS compliant equipment. Each successive iteration has improved performance and added new features. For instance, the jump from 1.0 to 2.0 resulted in more upstream bandwidth. The jump from 2.0 to 3.0 is one of speed. DOCSIS 3.0 bundles multiple channels for one data stream at the same time, which obviously increases bandwidth over a single channel.

How About Competing Modems?

First off, avoid anything that’s a hybrid cable modem/wireless router (otherwise known as a gateway). They can be hard to troubleshoot and if yours kicks the bucket, you’ll be left without any Internet service at all until a replacement can be found.

Other notable contenders include the Zoom 5341J, which is a popular one amongst the Comcast and Cox crowd but not quite as popular or written about as Motorola’s Surfboard line.

Given that the 6141’s closest competitor is the previous generation 6121, which has been around much longer and has more street cred, we picked the 6141 because it is, in theory, a faster portal. The 6141 can bond eight downstream channels and four upstream channels (8×4) topping out at over 300 Mbps down and 100 Mbps up, whereas the 6121 only supports four-channel bonding (4×4) both ways, reaching speeds of up to 160 Mbps down. It also only costs $10 extra so you might as well spend a little extra now to futureproof your setup.


Realistically, you’d never be able to reach those speeds regardless. Stephen Froehlich, the principal analyst at IHS’s Telecoms & Media group, had this to say:

“As far as I know, no US cable operator currently exploits the full capability of an 8×4 DOCSIS 3.0 modem, but they are instead only running a maximum of 3×1 on their plant. Therefore, an 8×4 modem will last longer, but it won’t run faster right now.”

So why stick with the 6141? Well, if you’re a Cox subscriber at the highest service tier (Ultimate), for example, you’re going to need an 8×4 cable modem starting next year. Todd C. Smith, the Media Relations Director at Cox told us the following:

“We have started to require DOCSIS 3.0 8×4 devices because of our plans to extend 100 Mbps speeds to additional markets next year (we currently offer it in one market on the residential side (Rhode Island) and multiple markets on the business side).

We are in the process of configuring all markets to bond 8 channels. Some are already there and all will be by end of next year.”

Based on region and tier of service, Time Warner Cable does require the use of an 8×4 cable modem, says a TWC rep. Comcast doesn’t require subscribers to have an 8×4 cable modem at this time and says it is only utilizing 4×4 channel bonding for its 200 Mbps service tier.

But it’s important to note that you don’t need to have a service plan that exceeds or even comes close to 100Mbps for your cable company’s infrastructure to require your modem to be DOCSIS 3.0 compatible. And while most of the major providers in the US haven’t fully deployed the DOCSIS 3.0 infrastructure or even support 8×4 channel bonding, they likely will within the next two years.

I also noticed some chatter on the forums that an 8×4 cable modem could deliver a more consistent service experience but that has very little to do with the cable modem itself. In fact, it really has more to do with your provider’s backend, says Froehlich.

“As for reliability, that has much more to do with the condition of a cable plant than anything else. What I see more often than anything else (in a Time Warner plant) is that the network equipment doesn’t have a battery backup, so its subject to power outages. As DSL is built to telco reliability standards (which includes many hours of battery backup), it tends to be more reliable in terms of uptime.”

Now, just because there’s a huge push to upgrade to DOCSIS 3.0 modems that doesn’t necessarily mean you need to fork over more than $100 right now. But here’s where it comes down your individual cable company and where you are located—

If you want to be safe, we recommend the 6141. But if you want to save $10 now, call your provider and ask if your tier of internet speed (or the tiers you want in the future) require DOCSIS 3.0 or if DOCSIS 2.0 will be okay—and for how long until DOCSIS 3.0 is required. Also ask how long DOCSIS 2.0 modems will be supported.

If you’re a Time Warner Cable subscriber, for instance, you could get by with a DOCSIS 2.0 modem for a while since the deployment of the 3.0 infrastructure isn’t yet ubiquitous. But certain tiers of service require a 3.0 cable modem (please see the chart below) even WITHOUT reaching the theoretical caps of the DOCSIS specification, because the carriers have infrastructure that requires more bonded channels.

The same goes for all the other major providers in the US, including Comcast even though the 3.0 infrastrastructure has been fully deployed. On August 29, Comcastposted to their Xfinity forums that customers with a DOCSIS 1.1 cable modem would need to upgrade to a DOCSIS 3.0 as the dated models would be end-of-lifed, meaning you won’t be able to use it with Comcast.

If you’re a Cox subscriber, you’ll have to pick based on your level of service. Again, only those with the Ultimate service tier are required to have an 8×4 cable modem.

If you’re a Charter customer it gets a bit tricky. New customers are issued a DOCSIS 3.0 cable modem and are not allowed to use their own. Existing customers who have been using their own modem and haven’t switched to Charter’s new plans can continue to switch up modems as they please. If you happen to be in the latter situation, then your best bet is the Motorola SB6121 or Linksys DPC3008 or 3010. But call Charter customer support before you go ahead and purchase a different cable modem. I received mixed answers from their PR team and online customer support. Unfortunately, it’s hard to say what cable modems they are issuing as it varies based on location, warehouse and technician but they appear to be issuing the Linksys DPC3000. Again, call ahead of time and inquire.

A good thing with renting: if you live in an area with a lot of weird power fluctuations and have seen a lot of cable modems get fried because of lightning storms and whatnot, renting means if it breaks the cable company will have to support and replace it.

Wrapping It Up

Few, if any, professional reviewers have taken the time to test cable modems. But we’re confident based on our research that the Surfboard 6141 is the best DOCSIS 3.0 cable modem available today for those with super fast Internet service. The slightly older 6121 is a more economical alternative for more economical service plans but that $10 in savings will definitely be cut short as the 6141 will stay relevant for at least a year or two longer when your carrier requires DOCSIS 3.0.

Note: The SB6141 now has one ethernet output port and the image has been updated to reflect that. This isn’t an issue for most people since you probably have a router for Wi-Fi anyway. It also got $30 cheaper so buying one makes more sense than ever.

This story originally ran in TheWirecutter on 1/19/2013 and is reprinted here with permission.


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