Head-to-head · Best Standalone DOCSIS 3.1 Cable Modems

Motorola MB7621 vs Motorola MB8611

Which is the better buy? Side-by-side on rating, price, strengths, and watch-outs — with the published ratings we averaged to get there.

The short answer

Motorola MB7621 comes out ahead by a clear margin (3.6 vs 2.7). The gap is mostly about temporary solution users on DOCSIS 3.0-compatible ISPs — read the strengths below before deciding.

Higher ratedRanked #2 in Best Standalone DOCSIS 3.1 Cable Modems

Motorola MB7621

3.6

$79.99as of Jul 7

The Motorola MB7621 is a DOCSIS 3.0 cable modem that delivers reliable performance in the right ISP environment, offering speeds between 500 and 900 Mbps with stable connections and cooler operation compared to some competitors. However, it's not suitable for plans exceeding 700 Mbps and faces obsolescence as Spectrum plans to end support by October 2026. Wirecutter selected it as 'the best modem for most people' in 2019, but its limitations make it a temporary solution for users planning future upgrades.

Strengths

— Operates on DOCSIS 3.0 with 24 downstream and 8 upstream channel bonding
— Runs on a Broadcom chipset that runs cooler than some rivals
— Provides stable connection in the right ISP environment with speeds between 500 and 900 Mbps

Watch-outs

— Not suitable for plans above 700 Mbps due to DOCSIS 3.0 protocol ceiling
— Spectrum is ending support for DOCSIS 3.0 modems on October 28, 2026

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Ranked #5 in Best Standalone DOCSIS 3.1 Cable Modems

Motorola MB8611

2.7

The Motorola MB8611 is a DOCSIS 3.1 modem offering fast internet speeds with a 2.5Gbps Ethernet port and support for up to 32 downstream and 8 upstream channels. Tech Reviews called it a great modem with backward compatibility and AQM for low-latency performance. However, some users have reported firmware-related stability issues, particularly with version 21.3.7, leading one user to switch to an Arris S34 after prolonged problems. It's approved for use with Comcast Xfinity, Cox, and Spectrum. This modem is ideal for users seeking high-speed internet but may not be suitable for those requiring voice capabilities or who experience firmware instability.

Strengths

— 2.5Gbps Ethernet port for high-speed wired connections
— Fast DOCSIS 3.1 speeds with support for 32 downstream and 8 upstream channels
— Backward compatible with DOCSIS 3.0

Watch-outs

— No voice capabilities
— Has firmware issues reported by some users (specifically 21.3.7 firmware causing instability)

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How they stack up

Motorola MB7621

The Motorola MB7621 is limited to DOCSIS 3.0 speeds, unlike the Arris SB8200 which supports DOCSIS 3.1, but it runs cooler than the Motorola MB8600. Unlike the Netgear CM1000, it doesn't support Gigabit speeds and is not future-proof, and unlike the Motorola MB8611, it lacks 2.5Gbps Ethernet support.

Motorola MB8611

The Motorola MB8611 supports 2.5Gbps Ethernet, unlike the Arris SB8200 which is capped at 1Gbps, but it's prone to firmware issues compared to the Netgear CM1000 which offers more stable performance. Unlike the Motorola MB8600, it doesn't support 6Gbps WAN speeds, and unlike the Arris SBG8000, it lacks integrated Wi-Fi.

Specs side-by-side

Spec	Motorola MB7621	Motorola MB8611
Docsis Version	DOCSIS 3.0	3.1
Max Download Speed	500-900 Mbps	2,500 Mbps
Ethernet Ports	Gigabit Ethernet ports	2.5Gbps Ethernet Port
Downstream Channels	24	32
Upstream Channels	8	8
Dimensions	7.25"L x 2.25"W x 7.88"H	7.25"L x 2.25"W x 7.88"H

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