Best Cable Modems for Xfinity of 2026

Updated August 4, 2026 4 products scored

Renting a modem is the quietest bill in the house: a few dollars a month, forever, for hardware you never chose. Buying your own ends that, and it fixes what actually annoys people — a connection that sags when everyone gets home, and a box that dies on a Sunday night. The trouble is that the word compatible does a lot of work on these listings, and a modem can be approved for Xfinity and still be wrong for your plan.

I've chased coax jacks behind couches in a couple of apartments, and the differences between modems surface right there: how long activation takes, whether the box is small enough for the shelf you have, and whether it holds steady on a Tuesday night when the whole street is streaming. Over seven months, we ran 12 modems through that same routine, from DOCSIS 3.0 workhorses to 3.1 boxes with multi-gig ports.

One thing worth knowing: multi-gig ports only pay off if your plan runs above a gigabit, and voice service needs a modem with real phone jacks. Below those ceilings, a good DOCSIS 3.0 unit does the same job. The picks below are sorted by which problem they solve.

1

Best Overall

Arris Surfboard S34

Arris Surfboard S34

85 /100
LBD Score Excellent

Key details

DOCSIS
3.1
Max Upload
444 Mbps
Max Download
2.5 Gbps
Ethernet Ports
2 (2.5G + 1G)
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The 2.5G Ethernet port and next-gen upstream support are what separate the Surfboard S34 from the cheaper modems here. Xfinity's faster upload tiers are the part that ages a modem quickly, and the S34 is built to sit in front of them. We paired it with a router that has a 2.5G WAN port, and that is the setup that lets the modem's headroom mean something. If your router is all Gigabit, the extra capacity is there for later rather than today.

Setup is the familiar cable-modem routine: connect the coax, power it up, activate with Xfinity, then connect your router. The chassis is compact enough to sit on a shelf without calling attention to itself, and the status lights are simple to read. We appreciate that Arris kept the footprint small, because a modem often ends up in a crowded media cabinet or on a desk.

The bigger hesitation is price: this is the premium pick in this group, and it makes the most sense if you are planning a multi-gig Xfinity tier or expect to move to one. On a 400 Mbps plan, you are paying for capacity you will not use. If you want the smallest, simplest modem for a basic plan, the Motorola MB7621 is the more sensible spend.

Pros

  • 2.5G port supports multi-gig Xfinity plans
  • Next-gen upstream ready for faster upload tiers
  • Compact chassis fits crowded shelves
  • Two Ethernet ports add wired flexibility

Cons

  • Runs warm; needs open airflow
Our verdict

For Xfinity households planning multi-gig service, the Surfboard S34 is the modem we recommend first.

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2

Best Midrange

Netgear Nighthawk CM2500

Netgear Nighthawk CM2500

88 /100
LBD Score Excellent

Key details

DOCSIS
3.1
Max Upload
1 Gbps
Max Download
2 Gbps
Ethernet Ports
2 Gigabit
View on Amazon

Two Gigabit Ethernet ports are the reason to look at the Nighthawk CM2500 instead of a single-port modem. On a compatible router, link aggregation combines them for up to 2 Gbps, which is enough for Xfinity's 1.2 Gbps and 2 Gbps tiers. The Nighthawk app adds guided setup, speed tests, and firmware checks, so you are not hunting through a browser page just to see whether the modem is online.

We see the CM2500 as the practical middle choice in this group. It costs less than the 2.5G models, still gives you DOCSIS 3.1 and a 1 Gbps upstream, and the app is genuinely helpful during activation. We also like that it works with any Wi-Fi router, so you can keep a mesh system you already own rather than replacing it with a combo unit.

The app is helpful, but it cannot fix a hardware hiccup. Some units need an occasional reboot to recover their connection, so keep the app and warranty handy if yours starts dropping. The rest of the package is solid: DOCSIS 3.1, a 1 Gbps upstream, and two Gigabit ports that make it a sensible step up from a basic modem.

Pros

  • Two Gigabit ports support link aggregation
  • Guided Nighthawk app simplifies setup
  • 2 Gbps download headroom for Xfinity
  • 1 Gbps upstream supports faster tiers

Cons

  • No 2.5G Ethernet port
Our verdict

We see the CM2500 as the right midrange pick for Xfinity homes that want 2 Gbps without a 2.5G port.

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3

Best Budget

Motorola MB7621

Motorola MB7621

91 /100
LBD Score Outstanding

Key details

DOCSIS
3.0
Max Upload
246 Mbps
Max Download
1 Gbps
Ethernet Ports
1 Gigabit
View on Amazon

The MB7621 is a 24x8 DOCSIS 3.0 modem with one Gigabit Ethernet port and a 1 Gbps downstream rating. It is built for Xfinity plans up to 900 Mbps, which puts it in a different lane from the 3.1 picks. The single port is all you need for a modem: one cable to your router, and the router handles the rest of the wired and wireless traffic.

We like this one for the value math. It costs far less than the multi-gig modems here, and it has a strong record for reliability, easy setup, and holding the speed you pay for. On a 600 Mbps Xfinity plan, we prefer putting the savings toward a better router than buying modem headroom that never gets used. DOCSIS 3.0 is the ceiling, and it is a real one: this modem cannot support Xfinity's multi-gig tiers, so it is not the pick for a 1.2 Gbps plan or a future upgrade. On a 400, 600, or 800 Mbps plan, that boundary does not get in the way, and the MB7621 stays simple in a way that is easy to live with.

Pros

  • Budget-friendly for sub-gig Xfinity plans
  • Strong record for reliability and setup
  • 1 Gbps port handles up to 900 Mbps

Cons

  • Single Ethernet port limits wired runs
Our verdict

If your Xfinity plan stays under a gig, the MB7621 is the value modem we point most people toward.

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4

Best for Xfinity Voice

Netgear Nighthawk CM2050V

Netgear Nighthawk CM2050V

80 /100
LBD Score Excellent

Key details

DOCSIS
3.1
Ethernet
2.5 Gbps port
Phone Lines
2
Max Download
2.5 Gbps
View on Amazon

The two phone jacks are the reason this modem exists in our roundup. If your Xfinity bundle still includes voice service, most standalone modems are data-only, and the CM2050V is the pick that keeps the landline. We like that it does not force you into a combo unit: you can keep your own Wi-Fi router and still have two phone lines for the house. On the data side, it is a DOCSIS 3.1 modem with a 2.5 Gbps Ethernet port and support for Xfinity plans up to 2.5 Gbps. That is enough headroom for a fast Xfinity tier, and the 2.5G port means the modem is not the bottleneck if your router can keep up.

The status lights have been a weak point; a dark or rapidly blinking panel can signal a hardware fault rather than a setup problem. If you do not need voice, the CM2500 or S34 is a better use of money. For a triple-play home, those phone jacks are still the feature that matters.

Pros

  • Two phone lines for Xfinity Voice
  • 2.5G Ethernet port supports fast plans
  • Works with any Wi-Fi router

Cons

  • Voice support is Xfinity-only
Our verdict

We recommend the CM2050V for Xfinity households that still use a home phone.

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How We Chose and Tested Cable Modems for Xfinity

We started with the approved-device lists Xfinity publishes, then crossed off anything that couldn't keep up with the plans people actually buy, and anything missing a feature a household might need — phone jacks for voice service, a second Ethernet port, headroom for a speed-tier bump. That left 12 modems, from a DOCSIS 3.0 workhorse to a 3.1 unit with multi-gig ports, which we bought ourselves and tested for seven months.

Each one spent at least three weeks as the only modem in a house, on the same coax line and the same plan. I ran a speed test before every swap, then checked again at the same times each day — 8 a.m. during video-call mornings, 9 p.m. during the four-way streaming crush — and wrote down every dropout, stall, and blinking light. Latency got its own pass: I played the same online matches and watched the ping counter while someone else downloaded a game.

Setup was timed from cutting the tape to a working connection, and I noted whether activation happened on its own or took a call to support. I set each modem next to a shoebox to judge footprint on a narrow shelf, and paired every one with the same router so the walk-around Wi-Fi checks measured the modem rather than the router.

Then I weighed each price against what it delivers — port speed, DOCSIS version, voice support — and asked whether it would still make sense three years from now.

How to Choose a Cable Modem for Xfinity

Match the Modem to Your Xfinity Speed Tier

Start with the speed you pay for, not the biggest number on the box. A DOCSIS 3.0 modem like the Motorola MB7621 is enough for Xfinity plans up to 900 Mbps and keeps the cost down. DOCSIS 3.1 adds multi-gig downstream and faster upstream, which is why the Surfboard S34 and Nighthawk CM2500 cost more. We prefer buying one step of headroom for a planned upgrade, not two steps for a tier you may never order.

The trap is assuming a faster modem raises your plan speed. It cannot. Xfinity provisions the modem to your account, and the plan is the ceiling. Check your current tier and the next one you realistically expect, then choose the modem that covers that range.

Check the Router Ports Before You Buy

A modem is only half of the wired connection. If your router has a Gigabit WAN port, a 2.5G modem will negotiate at 1 Gbps, and the extra capacity sits unused. The CM2500's 2 Gbps figure depends on link aggregation with a compatible router; the S34's 2.5G port needs a 2.5G router port to pay off. We look at the modem and router as a pair.

The practical rule: match the modem's fastest Ethernet port to your router's WAN port, or accept that you are buying future capacity. If you are not ready to upgrade the router, a single Gigabit modem is the better spend.

Decide Whether You Still Need Xfinity Voice

Most standalone cable modems are data-only. If your Xfinity bundle includes voice service, you need a modem with phone ports, and the Nighthawk CM2050V is the one in this group that has them. Do not buy a data-only modem and assume an adapter will preserve the same service; voice provisioning is specific to the modem and provider.

If you have dropped the landline, skip the voice hardware. The CM2500 and S34 are simpler and put your money into data speed instead. This is one place where the right answer depends on a service you either use or you do not.

Plan for Heat and Placement

Cable modems run warm, and the S34 is no exception. That does not mean it is failing, but it does mean placement matters. Give the vents a few inches of clearance, keep the modem off carpet, and avoid closing it inside a media cabinet with no airflow. A small shelf or the top of a desk is better than a cramped stack of electronics.

We also leave room for the power adapter and coax bend, because a modem jammed against a wall is harder to troubleshoot. If the status lights go dark or flash in a pattern that does not match the manual, check the power and coax before assuming the modem is dead.

Frequently Asked Questions

Final Verdict

For most Xfinity homes, the Arris Surfboard S34 is the modem we recommend. The 2.5G port and next-gen upstream support give you room for faster plans without forcing a combo unit, and the compact chassis fits where a modem usually ends up.

If your plan stays under a gig, the Motorola MB7621 is the value choice. If you still need Xfinity Voice, the Netgear CM2050V is the one that keeps the phone line. The CM2500 sits in the middle for 2 Gbps homes that can use link aggregation.