How we chose these, in the order the decision actually happens
We own none of these units and run no test lab, so nothing here is a throughput measurement of ours. What this page does is match a published port speed to a plan, check the standard, and be straight about who should not buy a modem at all. Five rules, in sequence.
1. Is there a fee to kill?This is the whole premise and it is the step every “best cable modem” list skips. The FCC now requires providers to publish a broadband consumer label for each plan, listing the monthly price and the equipment fees separately — so the answer is printed on a document your provider has to show you. On Spectrum’s Gig label the modem is included and the Wi-Fi service is priced at $0.00, with a $20.00 optional upgrade; on an older Xfinity plan there is usually a gateway line to be rid of, while the newest Xfinity plans bundle the gateway in. Find the line, or do not buy.
2. DOCSIS 3.1, with no exceptions.DOCSIS is the standard that governs what a cable modem can carry. CableLabs, the body that writes it, states that current DOCSIS 3.1 modems support capacities up to 5 Gbps downstream and 1.5 Gbps upstream, and that the DOCSIS 4.0 generation now arriving will reach 10 Gbps downstream and 6 Gbps upstream. Against that, a DOCSIS 3.0 unit is a modem you will replace. We checked the cheap 3.0 models still on sale — the Motorola MB7621 among them, listed for cable plans up to 900 Mbps — and they no longer undercut the cheapest 3.1 modem by enough to be worth the shorter life. That is why there is no DOCSIS 3.0 pick here.
3. The port has to match the plan. This is where money gets wasted in both directions. A modem with two gigabit ports cannot deliver more than a gigabit to one device no matter what the box says: the published multi-gig figure is an aggregate, and reaching it needs a router that supports link aggregation and a reason to bond two links. A modem with one 2.5 Gbps port gives a 1.2 or 2 Gbps plan somewhere to go. If you pay for 500 Mbps, neither matters and you should buy the cheap one.
4. It has to be on your provider’s own approved list.Every listing on this page names providers, and every one of those claims is the seller’s. The decision belongs to the ISP: Comcast’s page is blunt that if a device is not supported it “won’t work with Xfinity”, and Spectrum says symmetrical-speed plans require a Spectrum-provided modem. Look your exact model number up on your provider’s device list before ordering. A modem that is not on the list is not a bargain, it is a return.
5. Modem only. Never a combo. A modem-router gateway looks like a tidier purchase and is a worse one. The modem side of your setup is governed by a standard that changes every several years; the router side is where Wi-Fi generations, coverage and features move constantly. Keep them separate and you upgrade the half that has aged. Buy them welded together and you replace both, or you keep a dated router because the modem inside it still works.
The five modems, side by side
Read from each Amazon listing on the dated visit recorded against that product. Maximum rates are the maker’s published figure for the modem, never a speed your plan provides, and “Not published” means the listing does not state it.| Modem | DOCSIS | Ethernet ports | Max rate (maker) | Suits a plan of |
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| ARRIS SURFboard SB8200 | 3.1 | 2 x 1 Gbps (up to 2 Gbps aggregate, published) | Not published | Up to 1 Gbps |
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| Motorola B12 Cable Modem | 3.1 | 1 x 2.5 Gbps | 2500 Mbps, published | 500 Mbps to 2 Gbps |
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| Hitron CODA56 | 3.1 | 1 x 2.5 Gbps | 2.5 Gbps, published | 500 Mbps to 2 Gbps |
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| NETGEAR Nighthawk CM2500 | 3.1 | 2 x 1 Gbps | 2 Gbps, published | Up to 1 Gbps, or 2 Gbps with link aggregation |
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| ARRIS SURFboard S34 | 3.1, with Next Gen Upstream published | 1 x 2.5 Gbps + 1 x 1 Gbps | Multi-gig; no single figure in the listing title | 1 to 2 Gbps, heavy uploads |
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Read the last two columns together. The headline rate is the maker’s figure for the modem; the right-hand column is our read of the plan it genuinely suits, derived from the published port layout rather than the marketing number. The CM2500 is the clearest example of the gap: its published maximum is 2 Gbps, but that is spread across two gigabit ports, so a single device behind it sees a gigabit.
What a modem will not fix
Every coverage problem in your house is the router’s department. A modem terminates the coax and hands the connection to one Ethernet port. It has no radio, no antennas and no say in whether the far bedroom gets a signal. If the complaint you are trying to solve is “the Wi-Fi is bad upstairs”, a new modem will change nothing at all, and the money belongs in a better router or a mesh system instead.
A modem also will not raise the speed you are paying for. If your plan is 300 Mbps, a 2.5 Gbps port delivers 300 Mbps very efficiently. The only speed case where a modem is the culprit is the reverse one: an old rented box, or a DOCSIS 3.0 unit, capping a plan you have since upgraded. Which generation of router to pair with it is a separate decision, and Wi-Fi 6 vs Wi-Fi 7 is the short answer: the ports matter more than the radio for most households.
And it will not carry a bundled phone line. None of these units has telephone ports, so if your provider’s landline rides on your internet service, swapping the gateway for one of these takes the phone with it.
Who should not buy a cable modem at all
Anyone not on cable.This is the single most common wasted purchase in the category. If your service arrives on fiber — Verizon Fios, AT&T Fiber, Google Fiber, Frontier Fiber — or on DSL, fixed wireless, satellite or 5G home internet, a cable modem cannot connect to it. Fiber ends at an ONT and 5G home internet ends at a gateway with a SIM in it; neither speaks DOCSIS. The Hitron listing says “NOT for Fiber” in its own title for exactly this reason.
Most Spectrum customers. Spectrum supplies the modem as part of the service, which is on the face of its own FCC label. The fee worth attacking on Spectrum is the Wi-Fi service, and that is a router purchase, not a modem one.
Anyone on a plan that mandates provider equipment. Spectrum requires its own modem on symmetrical-speed plans, and providers rolling out multi-gig tiers commonly require their own hardware at the top end. Read the plan page before the modem page.
Anyone about to move.A modem is only portable within the same technology. Owning one is a win if you are staying on cable; it is a drawer ornament if next year’s address is on fiber.
The cord-cutter’s version of this question
If you are here because you have just canceled cable television, there is a specific trap waiting. Canceling the TV half of a bundle does not cancel the equipment rental. The box in the cabinet stays, the line on the bill stays, and in a lot of cases the provider has also just moved you onto an internet-only price with the equipment charge broken out where you can finally see it. That is the moment a modem purchase pays off fastest, and it is why our Xfinity walkthrough puts the equipment audit in the same step as the cancellation call.
The other half of that saving is the coax itself. Once the TV service is off, the cabling in your walls is yours to use, and a pair of MoCA adapters turns a dead cable outlet into a wired Ethernet link. That is the cheapest upgrade available to most houses after the modem swap, and it beats any amount of money spent on wireless gear.
Doing the swap without losing your internet for a day
The hardware part takes five minutes and the administrative part is the part people get wrong. The order that works:
Confirm the model is on your provider’s device list first, by model number, not by brand. Keep the rented box.Do not return it until the new modem is passing traffic — a failed activation with no modem in the house is a very long evening. Have your account details to hand, because activation means registering the new modem against your account, either in your provider’s app, on a web page, or on the phone. Power-cycle in order — coax in, power on, wait for the online light to stop blinking before you plug the router in. Then return the old unit and get a receipt, because unreturned-equipment charges are a well-worn billing dispute. Keep that receipt until you have seen one clean bill without the rental line on it.
DOCSIS 4.0: is it worth waiting?
No, for almost everybody.DOCSIS 4.0 is real and it matters: CableLabs describes it as delivering symmetrical multi-gigabit speeds, with capacities up to 10 Gbps down and 6 Gbps up against DOCSIS 3.1’s 5 Gbps and 1.5 Gbps. But the capability is useless until your provider has upgraded the network on your street, that rollout is measured in years, and the retail modems are priced like early hardware. A DOCSIS 3.1 modem bought today still exceeds what a 1 Gbps plan can use.
The one nuance worth paying for is upstream. Cable has always been lopsided — Spectrum’s own Gig label publishes typical speeds of 1045 Mbps down against 40 Mbps up — and the upstream improvements are arriving ahead of full DOCSIS 4.0 on some networks. That is the specific reason the ARRIS S34 is on this list with its published Next Gen Upstream support, and the specific reason it is the last pick rather than the first: it is the right buy only if you upload enough for 40 Mbps to be the thing that hurts.
Which one, in one line each
Plan up to 1 Gbps, which is most people: ARRIS SURFboard SB8200. DOCSIS 3.1 at the lowest price the standard sells for.
Plan between 1 and 2 Gbps: Motorola B12. One 2.5 Gbps port, mid price, nothing wasted.
Multi-gig plan, keeping the cost sane: Hitron CODA56.
First time doing this and you want a help line: NETGEAR Nighthawk CM2500.
You upload for a living, or you want one box for a decade: ARRIS SURFboard S34.
Your bill has no equipment line, or you are on fiber: buy none of them. Spend the money on the router instead, which is the part of the chain that decides what your house actually feels like.
