Top Picks at a Glance
| Product | DOCSIS | Max Plan Speed | Voice | Price | Best For |
|---|---|---|---|---|---|
| 1. ARRIS SURFboard SB8200 | 3.1 | Up to 2 Gbps | No | $170 | Best overall value |
| 2. Motorola MB8611 | 3.1 | Up to 2.5 Gbps | No | $200 | Future-proof gigabit |
| 3. Netgear Nighthawk CM2050V | 3.1 | Up to 2.5 Gbps | Yes (Xfinity Voice) | $280 | Xfinity Voice subscribers |
| 4. ARRIS SURFboard S33 | 3.1 | Up to 2.5 Gbps | No | $220 | Multi-gig plans |
| 5. Motorola MB7621 | 3.0 | Up to 600 Mbps | No | $95 | Sub-gigabit plans only |
Our Picks in Detail
- Speed overhead: Up to 2 Gbps
- Speed overhead: Up to 2.5 Gbps
- Speed overhead: Up to 2.5 Gbps
- Speed overhead: Up to 2.5 Gbps
- Speed overhead: Up to 600 Mbps
1. ARRIS SURFboard SB8200 — Best Overall
The SB8200 is the most reliable, widely-approved cable modem in the US. DOCSIS 3.1 covers any plan up to 2 Gbps, two 1 GbE ports for link aggregation if your ISP supports it, and approval at every major cable ISP (Xfinity, Spectrum, Cox, Mediacom, Optimum). The interface is plain but it's been bulletproof for years. If you want to buy a modem and forget about it for 6 years, this is the one.
Best for: 100 Mbps to 1 Gbps plans on any major US cable ISP.
2. Motorola MB8611 — Most Future-Proof
The MB8611 has a 2.5 GbE port (vs the SB8200's 1 GbE), giving headroom for multi-gig cable plans rolling out in 2025–27. DOCSIS 3.1 with all OFDM channels enabled means it's ready for the highest-tier cable plans available. The trade-off: $30 more than the SB8200 and slightly less common at retail.
Best for: Gigabit-plus subscribers who don't want to replace the modem when ISPs raise speeds.
3. Netgear Nighthawk CM2050V — Voice Service Compatible
If you have Xfinity Voice or another cable-based phone service, you need a modem with telephony support — most don't have it. The CM2050V has two RJ-11 phone ports and DOCSIS 3.1 internet. Setup is more complex (you have to provision the voice line through your ISP), but it's the cleanest modem option for anyone bundling cable internet with cable phone service.
Best for: Xfinity Voice or Spectrum Voice subscribers who want to ditch their rental modem.
4. ARRIS SURFboard S33 — Multi-Gig Ready
The S33 is the SB8200's bigger sibling — DOCSIS 3.1 with both a 2.5 GbE WAN port and a 1 GbE secondary port. For Xfinity's gigabit Pro plan or future multi-gig cable rollouts, the 2.5 GbE port is essential. Slightly more expensive than the MB8611 with similar specs, but ARRIS's track record at major ISPs is strong.
Best for: Future-proofing for multi-gig cable plans.
5. Motorola MB7621 — Best Budget Option
If your plan is 600 Mbps or under and you don't expect to upgrade in the next 2 years, the MB7621 is the cheapest legitimate modem. DOCSIS 3.0 is being phased out long-term, but for a sub-gigabit plan today, it works fine and pays for itself against rental fees in under a year. Avoid for any plan above 600 Mbps.
Best for: Sub-gigabit cable plans, tightest budget, short-term use.
How to Pick the Right Modem
- Check your ISP's approved modem list. Search "[ISP name] approved modem list" — Xfinity, Spectrum, Cox, etc. publish these. Buying a modem not on the list is a wasted $200.
- Match DOCSIS to your plan speed:
- ≤600 Mbps plan → DOCSIS 3.0 is fine (cheaper)
- 600 Mbps – 2 Gbps plan → DOCSIS 3.1 required
- Multi-gig (2.5+ Gbps) → DOCSIS 3.1 with 2.5 GbE port; DOCSIS 4.0 if available in your area
- Verify the WAN port speed. A DOCSIS 3.1 modem with only a 1 GbE port caps out at 940 Mbps real-world. For 1.2 Gbps+ plans, you need 2.5 GbE.
- Confirm voice support if needed. Telephony modems are a separate category; standard data modems don't have phone ports.
Modem-Router Combos: Skip Them
Modem-router combos look convenient but they're a bad deal long-term:
- Single point of failure. Modem dies? You also lose your router (or vice versa).
- Asynchronous upgrade cycles. Modems need replacing every 5–7 years; routers every 4–5. Combos force one cycle to match the other.
- Worse WiFi than dedicated routers. Combo units skimp on WiFi hardware to keep prices down.
Buy a modem (this list) plus a separate router. Always.
Setup Steps After You Buy
- Disconnect old modem. Note the MAC address of your new modem (printed on a sticker).
- Connect new modem. Coax in, Ethernet to your router, power on.
- Provision via ISP. Call ISP support or use their app. Provide the new modem's MAC address; they'll add it to your account.
- Wait for online lights. Provisioning typically takes 5–15 minutes.
- Run a wired speed test. Confirm you're getting plan speed.
- Return the rental. Stop the monthly fee — most ISPs require return within 30 days.
Frequently Asked Questions
Should I buy my own modem or rent from my ISP?
Buy. Cable ISPs charge $10–15/month for modem rental — that's $120–180/year. A solid DOCSIS 3.1 modem costs $130–220 and lasts 5–7 years. The break-even is 8–12 months; everything after that is pure savings, easily $500–800 over the modem's lifetime.
What DOCSIS version do I need?
Match your plan speed: DOCSIS 3.0 modems max out around 600–900 Mbps and are no longer sufficient for gigabit plans. DOCSIS 3.1 supports up to 10 Gbps downstream and is the right choice for any plan today. DOCSIS 4.0 is rolling out — only relevant if your ISP is launching multi-gig service.
Will any modem work with my ISP?
No — each ISP maintains an approved-modem list. Even if a modem is technically compatible, ISPs will refuse to provision it if it's not on their list. Always check Xfinity, Spectrum, Cox, etc.'s 'approved equipment' page before buying. All modems on this list are widely approved across major US cable ISPs.
Do I also need a router with my modem?
Yes if your goal is WiFi at home. A cable modem only converts the cable signal to Ethernet — it doesn't broadcast WiFi or do NAT routing for multiple devices. You either buy a separate router (recommended) or a modem-router combo (less flexible but simpler).
How long does a cable modem last?
5–7 years typically, though some last 10+. Modems mostly fail in two ways: components drifting out of spec (causing intermittent disconnects) or being deprecated by the ISP (DOCSIS 3.0 is being phased out). Replace when speeds consistently underperform your plan or the modem won't pass current ISP compatibility checks.