Best Comcast Modems Windows Central 2020

If you're looking to save money on Comcast without compromising on speed, buying your own cable modem is a great place to start. A modem takes the cable signal from outside and converts it to something your router or computer understands. The Motorola MB7621 has high-speed capabilities and a 2-year warranty from a trusted name in communications.

Best Overall: Motorola MB7621

Gigabit speed is a bit more than the most people need right now but considering how much our data needs have been increasing with streaming video and connected homes, it won't be too long before broadband internet needs to be faster and hit that threshold. Luckily, the MB7621 from Motorola can deliver speeds up to 940 Mbps down on Comcast Xfinity's Gigabit Speed plan.

Supporting DOCSIS 3.0, a connection standard that supports Comcast's fastest home speeds, the MB7621 provides top performance for all but the heaviest users. With 24 downstream channels, this modem can deliver downloads up to 1000 Mbps on an internet plan that supports those speeds. It is also capable of 246 Mbps upload speeds on eight upstream channels.

Five LEDs on the front of the modem make it easy to spot a connection problem and a well-ventilated case makes sure the modem stays cool enough for long operation. Connect this to a router or computer to complete your network.


  • Gigabit speed
  • DOCSIS 3.0
  • Two-year warranty
  • Well-placed LEDs


  • Large size

Best Overall

Motorola MB7621

Supports top speed

The Motorola MB7621 will support the top speed Comcast offers home users. This modem will be more than enough for any streaming or competitive gaming needs with plenty of speed and a gigabit Ethernet connection to your router.

Best Compact: Linksys CM3008

For some users, saving space is the most important consideration when choosing new technology. For these folks, a compact modem like the Linksys CM3008 is a great option. This modem is about the size of a pocket calculator, laying flat with all connections on the top end. The one main issue we have with this modem is that ventilation can get blocked easily. All modems need ventilation to stay cool and at this small size, so users will need to take care not to stack anything on top blocking the holes.

The CM3008 provides download speed up to 343 Mbps over its gigabit Ethernet port with eight downstream channels. It even supports upload speeds of 120 Mbps with four upstream channels. Even with its compact size, it manages to include five status lights for easy network diagnostics. If keeping a low profile with your networking equipment is a top priority, the Linksys CM3008 is a strong option.


  • Tiny size
  • DOCSIS 3.0


  • Ventilation easily blocked
  • One-year warranty

Best compact

Linksys CM3008

Small size, big power

Reduce the size of your networking setup with the Linksys CM3008. This modem keeps speed high enough for most users with downloads up to 343 Mbps and makes a great companion for a compact router.

Best future ready: Arris SB8200

Many people work from home and rely on the cloud for file storage or frequently need to stream large amounts of data. For those people staying on the cutting edge of speed, the Arris SB8200 modem boasts support for up to ten times Comcast's current Gigabit Speed plan. This modem pulls off this speed with support for DOCSIS 3.1 along with 32 downstream and eight upstream channels.

The SB8200 has dual gigabit Ethernet ports on the back that can be used together to improve access speed to the router. The front of the modem has only four status lights making troubleshooting slightly more cumbersome than others on this list, but not impossible. The rest of the modem is made of white plastic with plenty of ventilation on the sides and front.

The SB8200 is fully backwards compatible with DOCSIS 3.0 so even though, for now, the device isn't completely utilized, you can get the most out of your gigabit connection.


  • Fast DOCSIS 3.1
  • Dual Ethernet ports
  • Two-year warranty
  • Future-proof


  • Only four status lights
  • Not fully utilized

Best future ready

Arris SB8200

Fast for now and the future

The Arris SB8200 brings new DOCSIS 3.1 support and makes the most out of its 32 downstream and eight upstream channels. In a novel sized housing, this modem will be able to make the most of your current gigabit connection and future upgrades.

Best Value: Motorola MB7220

For a lot of people, the 343 Mbps download speed of the Motorola MB7220 is more than enough. That makes this modem a great way to save money over renting. With 8 downstream and 4 upstream channels at DOCSIS 3.0 speeds, this modem also offers a respectable 123 Mbps upload speed.

Falling in line with Motorola's other modem designs, the MB7220 has a well ventilated plastic housing with five LED status lights on the front. It also has gigabit Ethernet on the back to keep speeds high on the way to the modem. This modem is a good choice for someone that doesn't need much speed and wants to own their own equipment.


  • DOCSIS 3.0
  • Gigabit Ethernet
  • Two-year warranty


  • Limited speed upgrades
  • Large size

Best Value

Motorola MB7220

Just enough

The Motorola MB7220 offers speeds that are good enough for lower usage demands with its gigabit Ethernet port and 343 Mbps maximum download speed. This is a good way to move into owning your own networking equipment.

Bottom line

Any of these modems will help you take back control of your network and can even help you save money on rental fees. The Motorola MB7621 delivers all of the speed you can get on Comcast and will be fast enough for nearly everyone for quite a while. Whether you want to save some money or just take back control of your network with something strong to go with your new router, the MB7621 has everything you need to take advantage of the best speeds available today.

Credits — The team that worked on this guide

Samuel Contreras When Samuel is not writing about networking at Windows Central, he spends most of his time researching computer components and obsessing over what CPU goes into the ultimate Windows 98 computer. It's the Pentium 3.

We may earn a commission for purchases using our links. Learn more.