By Jim Kimble / May 27, 2021
Why you should replace a Comcast Xfinity modem
If you’re ready to ditch the monthly rental fees for a Comcast Xfinity modem, then replace it with a Motorola MB7621 cable modem.
Owning your own cable modem instead of renting one from Comcast Xfinity can save you $14 per month. The price for the MB7621 is currently just under $78, so you will recover the cost in about five and a half months.
In this guide, I’m providing recommendations of the best modems to use in 2021 for a few different Comcast Xfinity Internet plans. These recommendations come from my own testing in the last few years as a Comcast Xfinity subscriber and what I have used for friends and family.
Don’t buy a cable modem if your Xfinity service is on fiber. Comcast Xfinity does have a fiber-only network in some cities known as EPON (or Ethernet Passive Optical Network). The company says that there are no retail modems that support EPON technology.
Table of Contents
- Why you should replace a Comcast Xfinity modem
- Best cable modem for Comcast Xfinity
- Picking a compatible replacement
- Best Modem for Comcast Xfinity Gigabit plans
- Best modem for Comcast Xfinity Triple Play bundle
Best cable modem for Comcast Xfinity
For most people on non-gigabit plans, the Motorola MB7621 is the best choice for replacing a modem rented from Xfinity. The MB7621 supports speeds up to 600 megabits per second.
It is a DOCSIS 3.0 modem that has 24 downstream channels and eight upstream channels. The MB7621 also has a two-year warranty.
You won’t have to worry about compatibility issues. The MB7621 is certified by Comcast Xfinity, Cox, Spectrum (formerly Time Warner, Charter and Brighthouse), Suddenlink, Sparklight/Cable One and WOW.
The widespread compatibility gives you some flexibility if you have more than one internet service provider in your area.
Once you have picked a replacement modem of your own, you will also need to pick up a Wi-Fi router to be able to access the Internet wirelessly around your house. TP-Link’s Archer A20 has been my top pick over the last year, but I am just starting to test out new Wi-Fi 6 models.
Picking a compatible replacement
Before replacing the modem you’re renting from Comcast Xfinity, it’s important to review your monthly bill so you know exactly what kind of Internet plan you are currently on.
There are two more recommendations to consider if you are either on a gigabit speed plan or a Triple Play bundle. Comcast’s Triple Play bundle requires a modem with a VOIP telephone port.
DOCSIS 3.0 vs DOCSIS 3.1 Explained
The Internet plan you are on, or the one you plan to be on, will dictate whether you need a modem that supports DOCSIS 3.0 or DOCSIS 3.1.
DOCSIS is an abbreviation for Data Over Cable Service Interface Specifications.
Currently, most ISPs operate on the DOCSIS 3.0 standard. But DOCSIS 3.1 is expected to eventually become the new standard to support faster connections.
You will need a DOCSIS 3.1 modem for gigabit speeds from most internet service providers. The exception is for ISPs offering gigabit service through fiber. A cable modem won’t work with a fiber connection.
If you decide to buy a DOCSIS 3.1 model today, know that your equipment will be backwards compatible. So that means it will work fine if your ISP is currently operating on DOCSIS 3.0.
Comcast Xfinity Internet plans: Download vs Upload speeds
Comcast Xfinity generally offers three tiers of standalone Internet plans in the U.S.
- Performance Internet is 100 mbps
- Performance Pro is 200 mbps
- Blast! Internet is 400mbps
Internet plans are rated by a download speed and upload speed. Download speeds are important for tasks such as streaming video from Netflix or YouTube. Upload speeds matter for uploading a photo or video to Facebook.
For the purposes of streaming TV, you don’t need a lot of download speed to watch a show in High Definition.
Netflix recommends a download speed of five megabits per second for HD streaming, and 25 megabits per second for 4K/Ultra HD (UHD).
YouTube TV recommends a download speed of 13 megabits per second for streaming live TV in HD — even with other devices using the same network.
The average Internet speed in the U.S. is 99.3 Mbps, according to a 2021 survey by HighSpeedInternet.com, which maintains a database of Internet Service Providers.
Best Modem for Comcast Xfinity Gigabit plans
Comcast Xfinity is offering gigabit speeds in a number of cities across the U.S.
If you are going to pay for a gigabit plan, then you will want a DOCSIS 3.1 modem. The Motorola MB8600 is certified by Comcast Xfinity, and it’s one of the least expensive picks among similar equipment. It has a two-year warranty.
If your ISP provides gigabit internet on networks that still use DOCSIS 3.0 standard, the MB8600 will be compatible. A DOCSIS 3.1 modem should guarantee that you’re actually getting gigabit internet speed from your provider.
Best modem for Comcast Xfinity Triple Play bundle
While I advocate for cutting the cord from cable TV, and porting your landline to Google Voice, not everyone is a fan of dropping the cable bundle.
But if you are subscribing to a Comcast Xfinity Triple Play bundle, there is still a way to save some money by replacing your modem rental.
To do this, you will need a cable modem with a phone port. The Arris SURFboard SVG248AC has two VOIP telephone ports. And it is made specifically for Comcast Xfinity service.
It’s capable of 1 Gigabit download speeds. This is a combination modem and AC1750 router. The cable modem is DOCSIS 3.0 with 24 channels for downloads and 8 channels for uploads. There’s also the option to install a backup battery, which is sold separately.
For more news on streaming, how-to guides and reviews, head over to the main page of The Cord Cutting Report or follow the CCR on Google News.
Trevor Bartram says
We have Spectrum Internet only. They charge $5/month for modem/router rental. Our first Sagecomm router worked great until we started using MS Teams SW, it would cause disconnections. Spectrum changed it to a Netgear router, it worked great for a year then failed, then changed to a newer Sagecomm router and that’s been working great for a year. My point is, it’s worth $5/month to us to have Spectrum technicians available to diagnose these problems. Not sure how this would pan out for the non-technical person who buys their own equipment (is it the modem, cabling or router at fault?).
William Holmes says
Replaced COMCAST with NETGEAR C7100V. Pulled the plugs on the old modem, plugged in the C7100V. Connected my laptop to it. Followed instructions provided and it instantly connected my new modem to the system. Took 20
minutes. Working fine for the two days it has been up.
Purchased the NETGEAR C7100V at BEST BUY for $250.00.
Richard Bullock says
Does anyone have any tips on how to deal with Mediacom? Thanks.
Robert Miller says
2018. What are your recommendations to replace COMCAST Tripleplay modem and Wi-Fi router?
Andre Hodge says
I just have internet with Xfinity what modem should I use and what else i need to sream
Bob Pietrowsky says
I currently pay for Comcast triple play . I don’t use the phone at all , just have it to get a better price with triple play . My actual package is Preferred triple play . Costs are skyrocketing . Exactly what would you recommend to duplicate this package so that I can dump Xfinity once and for all ? Thanks , Bob
The Cord Cutter says
Bob, Check out my guide “Cord Cutting 2017” for some info on that. I think if you could get yourself a lower priced internet connection, you could easily use a live TV streaming platform like Sling TV or PlayStation Vue, which can give you a lot of the same channels. Also, consider an antenna. I use one to get a lot of great local channels.
Bob Pietrowsky says
Thanks , unfortunately , Xfinity is the only provider of residential internet in my area. No At+t , no Wow . I have read your report and got tons of great info , looks like Sling or DTN for me ! Bob
The Cord Cutter says
You might want to consider a DSL option. Depending on where you live, you might find a solid enough service like DSLExtreme or Toast.net for streaming.
Ken Nguyen says
I am currently using Arris TG862G-CT for voice and data. However, the device doesn’t have longer range. I want to upgrade the equipment to get better range. I’m thinking to use Arris TG862G-CT for voice and Netgear Nighthawk cable modem router C7800 for data. Please advise. Thank you.
The Cord Cutter says
Hi Ken, if you were just looking to improve the range of your WiFi, you might also want to consider a range extender. I’ve never added another WiFi router to a combo WiFi/modem before but I assume you can do it. The C7800 is a decent model, but an expensive choice.
Paula Torrey says
THANK YOU SO MUCH for your article. It is just what I needed to make an “intelligent” change from the impossible service we get with Comcast.
Jon Bailey says
How interchangeable is this information for Cablevision/Optimum (who knows what their name is)?
The Cord Cutter says
Hi Jon, The modem options for Optimum are pretty limited. You can find the list here: http://optimum.custhelp.com/app/answers/detail/a_id/3832/~/optimum-online-provided-modem
If you want to use one of the better modems in their list (Motorolla SVD6220), the company requires that you to rent one of theirs. I wish I had a better answer for you.