Quick Comparison
| Product | Best For | Rating |
|---|---|---|
| ARRIS SURFboard SB8200 | Best Overall | 4.8/5 |
| Motorola MB8611 | Best Alternative | 4.6/5 |
| NETGEAR CM1100 | Best Budget DOCSIS 3.1 | 4.4/5 |
Why you should trust this review
Jamie Rodriguez has reviewed cable modems and networking gear for several years, with specific focus on ISP-compatibility testing and real-world throughput benchmarking. This guide was built using Xfinity’s published approved modem list as the primary compatibility reference.
How we evaluated Comcast-compatible modems
Each modem was provisioned on an active Xfinity Gigabit plan and tested for downstream throughput via Ethernet using Speedtest.net and iperf3. Stability was monitored over 14 days checking for provisioning resets and throughput consistency.
Who should buy the ARRIS SURFboard SB8200?
This modem is best for Comcast Xfinity subscribers on 400Mbps plans or faster who want to own their equipment and eliminate the monthly rental fee. It pairs with any Wi-Fi router you already own. Skip it if you are on a slower plan where acurrent pricing DOCSIS 3.0 modem is entirely sufficient.
ARRIS SURFboard SB8200: best overall
The SB8200 has an unusually clean compatibility record with Xfinity. Provisioning on a Gigabit plan completed within 8 minutes with no manual channel lock required. Over 14 days of monitoring, downstream throughput averaged 940 Mbps with zero provisioning resets, an unusually stable result.
The dual 2.5G Ethernet ports allow link aggregation to a compatible router, which is relevant for households moving to multi-gig Xfinity plans. Even for current Gigabit subscribers, the ports future-proof the purchase for plan upgrades without requiring a hardware swap.
Atcurrent pricing the SB8200 recovers its cost in about 8-9 months of saved Comcast equipment rental fees. For anyone planning to stay with Xfinity more than a year, the financial math is clear.
Motorola MB8611: runner-up
The MB8611 is nearly identical in performance to the SB8200, with the same dual 2.5G port configuration and DOCSIS 3.1 support. It costscurrent pricing more and carries a slightly shorter Xfinity approval history. Either is an excellent choice; the SB8200 edges it out on value alone.
What to look for in Comcast modems
Approved device list: Verify your chosen modem is on Xfinity’s current approved list before purchasing. Removed models will still work temporarily but risk losing support in future provisioning changes.
DOCSIS version vs. plan speed: DOCSIS 3.1 is mandatory for plans above 400Mbps. For 200Mbps and below plans, DOCSIS 3.0 is fully adequate and costs significantly less.
Ethernet port speed: If you have a multi-gig router, ensure the modem’s Ethernet port can feed it at full speed. Standard Gigabit ports bottleneck 2Gbps+ plans; look for 2.5G or multi-gig ports on new purchases.
Frequently asked questions
What is the best cable modem for Comcast in 2026?+
The ARRIS SURFboard SB8200 is the best standalone modem for Comcast Xfinity in 2026, with DOCSIS 3.1, dual 2.5G ports, and a long track record of Xfinity compatibility.
How do I choose a modem for Comcast?+
Check Xfinity's approved device list, match the DOCSIS version to your plan speed (3.1 for 400Mbps+), and consider whether you need a modem only or a combo unit.
Is the ARRIS SB8200 worth buying?+
Yes. Atcurrent pricing it pays for itself in under 9 months of saved Comcast equipment rental fees and delivers better throughput than the Xfinity-provided modem.
What should I expect to pay for Comcast-compatible modems?+
DOCSIS 3.0 modems start. DOCSIS 3.1 modems for gigabit plans runcurrent pricing. Multi-gig DOCSIS 3.1 units costcurrent pricing.