Best DOCSIS 3.1 Modems (2026) for Xfinity, Spectrum & Cox

Last updated: September 2026

The best DOCSIS 3.1 modem for most people in 2026 is the Arris SURFboard S34. It handles multi-gig plans, has a 2.5 Gigabit Ethernet port, and supports the faster upload tiers cable ISPs are rolling out. The Hitron CODA56 is the value pick, the Arris SB8200 is the budget choice for gigabit plans, and the Arris G36 is the pick if you want the modem and Wi-Fi 6 router in one box.

Every modem below is a cable modem. None of them work with fiber, DSL, or satellite service, and most do not support bundled voice plans. Fiber providers like AT&T Fiber and Verizon Fios use an ONT instead of a modem. Confirm your provider and speed tier before ordering.

What Is DOCSIS 3.1?

DOCSIS 3.1 is the standard that governs how a cable modem talks to your provider's network over coaxial cable. It replaced DOCSIS 3.0 with a more efficient signal called OFDM, which packs far more data into the same cable. On paper the standard supports up to 10 Gbps downstream; in practice, US cable plans on 3.1 top out around 2.5 Gbps down, with uploads from 35 Mbps on older networks to 1 Gbps where high-split upgrades are live.

Every DOCSIS 3.1 modem is backwards compatible with DOCSIS 3.0 networks, so it works today even if your neighborhood has not been upgraded, and it keeps working as your ISP moves forward.

Why DOCSIS 3.1 Is Still the Right Buy in 2026

DOCSIS 3.1 remains the standard for customer-owned cable modems in 2026. The next generation, DOCSIS 4.0, is live in a growing number of markets, but as of this update nearly all DOCSIS 4.0 service runs on ISP-issued gateways, and retail DOCSIS 4.0 modems have yet to reach shelves in volume. Our DOCSIS 4.0 explainer covers the technology, and our rollout tracker by provider shows where it is available.

The money math has changed. On legacy plans, gateway rental still adds up: as of mid-2026, Xfinity charges $15 to $25 per month on plans sold before mid-2025, Cox charges $15 for its Panoramic gateway, and Spectrum adds a $10 monthly fee for its Advanced WiFi, per each provider's published equipment pricing. On those plans, a modem you own pays for itself within the first year. Newer bundled plans, like Xfinity's Everyday Pricing, fold the gateway into the monthly price, so the argument there is different: owning your equipment is about control, privacy, and choosing better hardware than the default box.

How We Pick

This list comes from three sources. First, the ISP approved lists, which we audit against our guides every time a provider adds or retires a model. Second, the manufacturer spec sheets, which decide the speed tier and upload capability of each modem. Third, our own refurbishing bench. Since 2015 we have been testing, resetting, and re-homing cable modems in the US, and models like the Arris S33, SB8200, and DG3450 pass through our hands in volume. That means we see which units activate cleanly on the first try, which ones come back, and which ones hold their signal levels over years of service. A modem earns a spot here when it does well on all three counts, and it loses one when an ISP drops it or the units we handle stop holding up.

The Best DOCSIS 3.1 Modems of 2026

1. Arris SURFboard S34: Best Overall

The S34 is the top pick for 2026. It handles plans up to 2.5 Gbps, includes both a 2.5 Gigabit and a 1 Gigabit Ethernet port, and supports mid-split technology, which unlocks the faster upload tiers on plans like Xfinity Next-Gen. It runs a stable Broadcom chipset, sets up in minutes through the SURFboard Central app, and is certified for Xfinity, Cox, and Spectrum. One modem that covers every current cable plan.

Check Availability: Arris SURFboard S34

2. Arris SURFboard S33: Best Runner-Up

The S33 is nearly identical to the S34 without the enhanced upload support. Same 2.5 Gigabit port, same stable Broadcom chipset, usually a lower price, and a long track record of steady, low-latency performance. It is certified for Xfinity, Cox, and Spectrum, but Xfinity does not list it for its Next-Gen upload tiers. If your plan advertises faster uploads, buy the S34 instead; if not, the S33 is the smarter spend, and it is one of the models we refurbish most often.

Check Availability: Arris SURFboard S33

3. Netgear Nighthawk CM3000: Best for Fast Uploads

The CM3000 is built for households that upload as much as they download: content creators, remote workers on constant video calls, anyone pushing large backups to the cloud. It supports both mid-split and high-split configurations, handles download plans up to 2.5 Gbps, and includes a 2.5 Gigabit port. It costs more than most modems here, but nothing on this list is better prepared for the upload upgrades Xfinity and Cox are rolling out.

Check Availability: Netgear Nighthawk CM3000

4. Hitron CODA56: Best Value

The CODA56 gives you a 2.5 Gigabit port and mid-split capability at a price that undercuts the bigger brands. It supports plans up to about 2.3 Gbps and is certified for Xfinity, Spectrum, and Cox. It skips the extras, and for anyone on a gigabit plan who wants the most performance per dollar, it is the smartest buy of 2026.

Check Availability: Hitron CODA56

5. Motorola B12: Best Compact Multi-Gig

The B12 is Motorola's direct successor to the popular MB8611. It pairs DOCSIS 3.1 with a 2.5 Gigabit Ethernet port, reaches downstream speeds just below 2,500 Mbps with uploads up to 800 Mbps where supported, and fits a smaller footprint than nearly anything else in its class. It is approved for Xfinity, Cox, Spectrum, RCN, and Astound, and it carries a 2-year warranty, which is longer than most of this list.

Check Availability: Motorola B12

6. Motorola MB8611: Proven Low-Latency Pick

The MB8611 pairs a 2.5 Gigabit Ethernet port with a strong record of flat, reliable latency during gaming, streaming, and video calls. It supports downloads just under 2.5 Gbps and uploads up to 800 Mbps where supported, and it is approved for Xfinity, Cox, and Spectrum. The B12 above is its successor, but while the MB8611 is available it remains a dependable, well-supported choice.

Check Availability: Motorola MB8611

7. Netgear Nighthawk CM2500: Best for Xfinity Upload Tiers

The CM2500 is a mid/high-split modem designed around the newer upload-focused plans, including Xfinity tiers with 100 Mbps uploads. It reaches 2 Gbps downloads by combining its two 1 Gigabit ports through link aggregation, so pair it with a router that supports that feature to get full speed. Not compatible with Xfinity Voice plans.

Check Availability: Netgear Nighthawk CM2500

8. Arris SURFboard SB8200: Best Budget Pick for Gigabit Plans

The SB8200 is the classic DOCSIS 3.1 modem: widely deployed, extremely stable, and compatible with every major cable ISP. It has two 1 Gigabit ports and no multi-gig or mid-split support, which makes it the right choice for standard plans from 300 to 1,000 Mbps where you want reliability at the lowest cost.

Check Availability: Arris SURFboard SB8200

9. Motorola MB8600: Budget Classic

The MB8600 is another proven budget option for gigabit-and-under plans. It runs a secure Broadcom chipset, holds latency down under load, and works with Xfinity, Cox, and other major providers. If you see it priced below the SB8200, grab it.

Check Availability: Motorola MB8600

Best DOCSIS 3.1 Modem Router Combos

A combo puts the modem and the Wi-Fi router in one box: fewer cables, one outlet, one device to manage. The trade-off is that you replace both halves at once when either one ages out. These three are the combos we would buy in 2026.

10. Arris SURFboard G36: Best Multi-Gig Combo

The G36 pairs a DOCSIS 3.1 modem with a Wi-Fi 6 AX3000 router and a 2.5 Gigabit Ethernet port, plus four 1 Gigabit ports for wired devices. It supports cable plans up to 1.2 Gbps and is compatible with Xfinity, Cox, and Spectrum. If you want one box and your plan is at or above gigabit, this is the combo that will not bottleneck it.

Check Availability: Arris SURFboard G36

11. Arris SURFboard G34: Best Combo for Gigabit and Under

The G34 combines a DOCSIS 3.1 modem with a Wi-Fi 6 router, delivering wireless speeds up to 3 Gbps and support for cable plans up to 1 Gbps. It is compatible with Xfinity, Cox, and Spectrum, and setup takes minutes through the SURFboard Central app. For plans up to a gigabit it costs less than the G36 and gives up nothing you would notice.

Check Availability: Arris SURFboard G34

12. Arris DG3450 (Refurbished): Best Combo Value for Spectrum

The DG3450 is the budget path to a one-box setup on Spectrum: a DOCSIS 3.1 modem and dual-band Wi-Fi router in a single gateway, with four Gigabit Ethernet ports and MoCA 2.0 support for stable whole-home coax networking. Because it replaces both the modem and the router, it also replaces Spectrum's $10 per month Advanced WiFi fee with equipment you own. This is a Spectrum-specific pick: it is not the right buy for Xfinity households, so confirm your provider before ordering. We stock professionally refurbished units, each tested in the US and backed by our 90-day warranty. See our Spectrum modem-router combo guide for the full comparison.

Check Availability: Arris DG3450 (Refurbished)

Comparison Table: Best DOCSIS 3.1 Modems of 2026

Price tiers are relative to the other modems on this list. Current prices and stock for every model are on the DOCSIS 3.1 modem collection page.

Model	Best For	Max Plan Speed	2.5G Port	Next Gen Uploads	Price Tier
Arris S34	Overall	2.5 Gbps	Yes	Yes (mid-split)	Premium
Arris S33	Runner-up	2.5 Gbps	Yes	No	Mid
Netgear CM3000	Heavy uploads	2.5 Gbps	Yes	Yes (mid/high-split)	Premium
Hitron CODA56	Value	2.3 Gbps	Yes	Yes (mid-split)	Mid
Motorola B12	Compact multi-gig	2.5 Gbps	Yes	No	Mid
Motorola MB8611	Low latency	2.5 Gbps	Yes	No	Mid
Netgear CM2500	Xfinity upload tiers	2 Gbps (link aggregation)	No (2x 1G)	Yes (mid/high-split)	Mid
Arris SB8200	Budget gigabit	1 Gbps	No	No	Budget
Motorola MB8600	Budget classic	1 Gbps	No	No	Budget
Arris G36	Multi-gig combo	1.2 Gbps	Yes	No	Premium
Arris G34	Gigabit combo	1 Gbps	No	No	Mid
Arris DG3450 (Refurb)	Spectrum combo value	1 Gbps	No	No	Budget

Next Gen Uploads means the modem supports mid-split or high-split configurations where the ISP has upgraded its network. Confirm your exact model on your provider's approved list before buying.

Best DOCSIS 3.1 Modem by ISP

The right pick shifts a little by provider, because each ISP certifies its own list and sets its own rules for customer-owned equipment.

Xfinity

The Arris S34 is the best DOCSIS 3.1 modem for Xfinity because it is listed for the Next-Gen upload tiers. On a standard gigabit or slower plan, the S33 or CODA56 costs less and works just as well. Browse our Xfinity compatible modems.

Spectrum

Spectrum authorizes retail modems on plans up to 1 Gig, and its 2 Gig plan requires Spectrum-provided equipment. The S33, MB8611, and CODA56 are the strongest standalone picks, and the refurbished DG3450 is the best way to drop the Advanced WiFi fee in one box. See our Spectrum modem collection and our Spectrum picks by speed tier.

Cox

Cox certifies most of the modems on this list, including the S34, S33, CM3000, CODA56, and SB8200, and supplies its own hardware for bundled voice. Browse our Cox compatible modems.

Optimum

Optimum keeps a shorter retail list than the big three. The SB8200, S33, and MB8611 are the models most often listed, but Optimum approvals vary by region, so confirm at your address before ordering. Browse our Optimum compatible modems.

Mediacom and other providers

Mediacom trimmed its approved list in late 2024 and now favors newer DOCSIS 3.1 models, so check its current list before buying. Our Mediacom collection is filtered to models that appear on it.

How to Choose a DOCSIS 3.1 Modem

Match the modem to your plan speed

Buying a multi-gig modem for a 300 Mbps plan wastes money, and buying a gigabit modem for a 2 Gbps plan wastes speed. Check your bill for your plan tier, then pick the cheapest modem on this list that comfortably covers it.

Check for a 2.5 Gigabit Ethernet port

Gigabit plans are often over-provisioned, meaning the speed delivered to your home can exceed 1,000 Mbps. A standard 1 Gigabit port caps you around 940 Mbps in practice. If your plan is 1 Gbps or faster, a 2.5 Gigabit port ensures you receive everything you pay for.

Look for mid-split support if your ISP offers faster uploads

Cable uploads sat around 35 Mbps for years. Mid-split and high-split technology raises that to 100 Mbps or more where ISPs have upgraded their networks. If your provider advertises enhanced or Next-Gen upload speeds, choose the S34, CM3000, CM2500, or CODA56.

Prefer a Broadcom chipset

Every pick on this list runs a Broadcom chipset. Older modems built on the Intel Puma 6 platform became known for latency spikes and jitter that no firmware update fully cured, and while Puma 7 units behave better, Broadcom has the cleaner record for gaming, video calls, and anything else where a steady ping matters. If a modem you are considering is not on this list, check which chipset it uses before you buy.

Know your ISP's limits on customer-owned equipment

Spectrum only authorizes retail modems on tiers up to 1 Gig; its 2 Gig plan requires Spectrum-provided equipment. Spectrum also charges $10 per month for its Advanced WiFi router, which is why a combo like the DG3450 pays off fastest there. Cox supplies its own hardware for bundled voice service. Rules like these change by provider and by plan, which is one more reason the approved list, not the spec sheet, gets the final word.

Remember these are modems, not routers

Except for the G36, G34, and DG3450 combos, every modem here needs a separate Wi-Fi router to create a wireless network. If you already own a good router, a standalone modem is the better setup. Browse our wireless router collection to pair one up.

Check Your ISP's Approved List Before You Buy

A cable modem only works if your provider will activate it, and each ISP maintains its own certified device list that changes several times a year. We audit those lists against this guide regularly. Before ordering, confirm your exact model on our Xfinity approved modem list, Cox approved modem list, or Spectrum approved modem list, each of which links the provider's official page. Cox, for example, publishes its authoritative list at cox.com, and only models on it will provision.

Frequently Asked Questions

Do I need a DOCSIS 3.1 modem?

If you are buying a cable modem in 2026, yes. Xfinity, Spectrum, and Cox are actively retiring DOCSIS 3.0 hardware from their approved lists, and Spectrum ends DOCSIS 3.0 support entirely on October 28, 2026. A DOCSIS 3.1 modem works on every current cable plan and will not need replacing when your ISP finishes the transition.

What speeds does DOCSIS 3.1 support?

The specification allows up to 10 Gbps downstream and 1 to 2 Gbps upstream. Real plans are lower: US cable ISPs sell DOCSIS 3.1 tiers up to about 2.5 Gbps down, and uploads range from 35 Mbps on legacy networks to 100 to 200 Mbps on mid-split and up to 1 Gbps on high-split. The modem's Ethernet port also matters; a 1 Gigabit port caps wired speed near 940 Mbps regardless of plan.

Are DOCSIS 3.1 modems backwards compatible?

Yes. Every DOCSIS 3.1 modem is fully backwards compatible with DOCSIS 3.0 networks and plans. If your area has not been upgraded yet, a 3.1 modem simply runs at 3.0 speeds until the network catches up, so there is no downside to buying 3.1 now.

Is a DOCSIS 3.1 modem worth it?

Yes, for almost everyone. The price gap between DOCSIS 3.0 and 3.1 modems has nearly closed, and a 3.1 modem eliminates rental fees while staying compatible through your ISP's network upgrades. The only exception is a plan you know you are canceling within a few months.

DOCSIS 3.1 vs 4.0: is DOCSIS 3.1 obsolete in 2026?

No. DOCSIS 3.1 remains the standard for customer-owned cable modems in 2026. DOCSIS 4.0 service is expanding, but it runs almost entirely on ISP-issued gateways today, and retail DOCSIS 4.0 modems have yet to arrive in volume. Our DOCSIS 3.1 vs 4.0 guide covers whether to wait, and our DOCSIS 4.0 modem guide tracks the retail rollout.

What is the difference between DOCSIS 3.0 and DOCSIS 3.1?

DOCSIS 3.1 is roughly ten times faster than DOCSIS 3.0, with lower latency and better efficiency. Major ISPs are actively retiring DOCSIS 3.0 hardware; Xfinity removed dozens of older DOCSIS 3.0 models from its approved list in two rounds in April and July 2026. For any new purchase, 3.1 is the minimum standard.

Which DOCSIS 3.1 modem is best for Xfinity?

The Arris SURFboard S34 is the best DOCSIS 3.1 modem for Xfinity in 2026 because it supports Next-Gen upload tiers. For standard Xfinity gigabit plans, the Arris S33 or Hitron CODA56 also work well. Confirm your pick on our Xfinity approved modem list before buying.

Which DOCSIS 3.1 modem is best for Spectrum?

The Arris S33, Motorola MB8611, and Hitron CODA56 are the best standalone DOCSIS 3.1 modems for Spectrum plans up to 1 Gig, and the refurbished Arris DG3450 is the best combo if you want to drop the Advanced WiFi fee. Spectrum's 2 Gig plan still requires Spectrum equipment. Confirm on our Spectrum approved modem list.

Which DOCSIS 3.1 modem router combo is best?

The Arris SURFboard G36 is the best DOCSIS 3.1 modem router combo for gigabit and faster plans because of its 2.5 Gigabit port and Wi-Fi 6 AX3000 router. The G34 is the better value on plans up to 1 Gbps, and the refurbished DG3450 is the cheapest way to replace both boxes on Spectrum.

Do any DOCSIS 3.1 modems support phone service?

Very few retail ones. DOCSIS 3.1 modems with telephone ports, sometimes called EMTAs, are almost all issued by the ISP; Spectrum supplies its own voice modem (such as the Arris TM3402) to phone customers, and Xfinity Voice requires an Xfinity-approved voice device from a short list. Most households keep the ISP's device for the phone line, or drop landline service, and buy their own modem for data.

Do I still need a router with a DOCSIS 3.1 modem?

Yes, unless you buy a combo unit like the Arris G36, G34, or DG3450. A modem connects your home to your ISP, and a router creates the Wi-Fi network your devices use. Standalone modems have no Wi-Fi built in.

How much money does buying your own modem save?

On legacy plans, most cable providers charge $10 to $25 per month for equipment, or $120 to $300 per year, so an owned modem typically pays for itself within a year. On newer bundled plans that include the gateway, the savings are smaller or zero, and the case for ownership is control, privacy, and better hardware instead.

What is a mid-split modem?

A mid-split modem dedicates more of the cable frequency spectrum to uploads, raising upload speeds from around 35 Mbps to 100 to 200 Mbps on supported networks. High-split goes further, up to 1 Gbps in some areas. You only benefit if your ISP has upgraded your neighborhood.

Are refurbished DOCSIS 3.1 modems worth buying?

Yes, when they are professionally tested and warranty-backed. A refurbished DOCSIS 3.1 modem delivers identical performance to a new unit at a lower price, and it keeps working hardware out of landfills. Every refurbished unit we stock, including the DG3450 gateway above, is tested in the US and covered by our 90-day warranty.

Where can I buy a DOCSIS 3.1 modem?

Our DOCSIS 3.1 modem collection carries every model on this list, refurbished or new, with filters for your provider and price. Orders over $49 ship free, refurbished units carry a 90-day warranty, and returns are accepted within 30 days.

Do I need a special modem for gaming?

No. Every DOCSIS 3.1 modem is required by the CableLabs specification to include anti-bufferbloat Active Queue Management, documented in RFC 8034, so the machinery for low latency ships in all of them; whether it runs is governed by your ISP's configuration. Our gaming modem guide covers what moves your ping.