Buying a cable modem? Start with DOCSIS.

DOCSIS is the standard that controls how your cable modem talks to your internet provider. The version of DOCSIS your modem uses decides how fast it can go and how “future-proof” it is.

DOCSIS 3.0 – older, still fine for many basic plans
DOCSIS 3.1 – best all-around choice for most people today
DOCSIS 4.0 – next-gen, still rolling out in most areas

Note: your actual speed also depends on your provider, wiring quality, and the plan you pay for.

Quick speed idea (theoretical maximums):

3.0: up to ~1 Gbps down 3.1: up to ~10 Gbps down 4.0: up to ~10 Gbps down / 6 Gbps up

You will not see these numbers at home. Your ISP will limit speeds to the plan you’re on.

What is DOCSIS, in simple terms?

DOCSIS stands for Data Over Cable Service Interface Specification. It is just the “rulebook” for how internet data is sent over coaxial cable (the same cable used for TV).

Your modem must support the DOCSIS version your provider uses.
Newer DOCSIS versions can handle faster speeds and more efficient use of the cable line.
You can often keep your own modem and avoid monthly rental fees, if it’s compatible.

DOCSIS versions – what’s the practical difference?

DOCSIS 2.0 (older)

Mostly legacy gear now

Single channel – limited download and upload speeds.
Generally not recommended for new purchases.
Often not approved for newer speed tiers.

DOCSIS 3.0

Common, but slowly being phased out

Uses “channel bonding” to combine multiple channels.
Enough for many plans up to around 300–600 Mbps, depending on model.
Cheaper, but not very future-proof.

DOCSIS 3.1

Best choice for most home users

Designed for gigabit and multi-hundred-meg plans.
Better efficiency, often lower latency.
Backwards-compatible with DOCSIS 3.0 networks.

DOCSIS 4.0

Newer, still limited availability

Aims for much higher upload speeds.
Useful if your provider offers very high multi-gig plans.
For most people today, still “nice to have”, not required.

Example modem types (by DOCSIS version)

These are category examples so you can see what kind of specs go with each DOCSIS version. Actual models are listed in the “Popular models (2025)” section below.

DOCSIS 3.0 examples

Good for lower-to-mid speed plans

16×4 or 24×8 channel modems – fine for 100–300 Mbps plans.
32×8 channel modems – often used for 300–600 Mbps plans.
Best for light streaming, browsing, and casual gaming.

DOCSIS 3.1 examples

Best match for 300 Mbps to 1 Gbps plans

Usually marketed as “gigabit cable modem”.
Good for multiple 4K streams, work-from-home, online gaming.
Most cable companies are moving toward 3.1 as the new standard.

DOCSIS 4.0 examples

Early stage / premium gear

Targeted at multi-gigabit download and much faster upload.
Requires your provider to actually support DOCSIS 4.0.
Overkill if your plan is under 1 Gbps.

Popular DOCSIS modem models in 2025

These are widely used or frequently recommended models as of this year. Always check your own cable provider’s approved modem list before buying.

Modem only (no Wi-Fi)

Pair these with your own router

ARRIS SURFboard S34
DOCSIS 3.1 – modem only
Best for: gigabit & multi-gig tiers (up to ~2.5 Gbps with 2.5G port).
Good pick if you want something very current and multi-gig ready.
ARRIS SURFboard S33
DOCSIS 3.1 – modem only
Best for: 500 Mbps to 1+ Gbps plans.
Very common recommendation on ISP lists and forums.
Motorola MB8611
DOCSIS 3.1 – modem only
Best for: 1 Gbps and multi-gig plans (2.5G Ethernet port).
Solid option if you need more than basic gigabit.
NETGEAR CM2000 / CM3000
DOCSIS 3.1 – modem only
Best for: advanced multi-gig tiers when your ISP supports them.
Overkill for sub-gigabit plans.
NETGEAR CM500
DOCSIS 3.0 – modem only
Best for: budget plans up to ~300 Mbps.
Simple, inexpensive choice where speeds are lower.
Motorola MB7621
DOCSIS 3.0 – modem only
Best for: 100–400 Mbps level plans.
Good fit for small households that don’t need gigabit.

Modem + Wi-Fi built in (gateway)

All-in-one units – modem plus wireless router

ARRIS SURFboard G34
DOCSIS 3.1 – modem + Wi-Fi 6
Best for: plans up to 1 Gbps, small to medium homes.
Nice “one box” upgrade instead of separate modem and router.
ARRIS SURFboard G54
DOCSIS 3.1 – modem + Wi-Fi 7
Best for: fast plans (up to ~2.5 Gbps) with lots of Wi-Fi devices.
For people who want the newest Wi-Fi standard in a combo unit.
NETGEAR Nighthawk CAX80
DOCSIS 3.1 – modem + Wi-Fi 6
Best for: gigabit and above, larger homes.
High-end gateway aimed at heavy users and many devices.
Motorola MG8725 / MG8702
DOCSIS 3.1 – modem + Wi-Fi
Best for: 500 Mbps to 1 Gbps plans.
Good “plug it in and you’re done” combo option.

Tip: modem-only + separate Wi-Fi router gives more flexibility. Gateways (modem + Wi-Fi) are simpler, but upgrades later are a little less flexible.

Which modem should I actually buy?

You don’t need to chase the biggest possible numbers. Use this as a simple guide:

Under 100 Mbps plan: Old 3.0 will work, but 3.1 is still a nicer upgrade.
100–300 Mbps plan: 3.0 or 3.1 both okay; go 3.1 if prices are close.
300–800 Mbps plan: 3.1 is strongly recommended.
1 Gbps or higher plan: 3.1 minimum, 4.0 only if your ISP supports it.

        Important:
        A faster modem does not automatically give you faster internet.
        Your provider must offer the speed and configure your modem for that plan.
      

Quick compatibility checklist

Check that the modem model is on your ISP’s approved list.
Match DOCSIS version to your speed plan (ideally 3.1+ for 300 Mbps or higher).
Decide if you want a modem only or a modem + Wi-Fi combo.
If you use your own router, a simple “cable modem only” is usually easier.
Look at the number of Ethernet ports (1 vs 2) if you plan to use link aggregation.