Motorola SURFboard SB6121
Score: 62/100
Motorola MT7711
Score: 73/100Rankings
The Motorola MT7711 is an all-in-one DOCSIS 3.0 modem, AC1900 Wi-Fi router, and two-port Xfinity Voice solution. Its 600 Mbps speed ceiling and Xfinity-only certification restrict its use for higher-speed or non-Xfinity services. Best suited for Comcast customers needing integrated voice and Wi-Fi.
The Arris SB6121 is a DOCSIS 3.0 cable modem with ENERGY STAR efficiency and front-panel LEDs, delivering up to 172 Mbps downstream for mid-tier broadband. Its limited channel bonding and lack of Wi-Fi make it unsuitable for modern high-speed plans. Ideal for budget-conscious households with basic internet needs.
| Attribute | | |
|---|---|---|
172 Mbps | 1,000 Mbpsbest | |
131.072 Mbps | 246 Mbpsbest | |
1 ports | 4 portsbest | |
| ↓ lower better | — | 48 Wbest |
| ↓ lower better | 0.454 kgbest | 1.718 kg |
1 years | 2 yearsbest |
Click an attribute name to sort · Green = best, red = worst (relative to this comparison)
| Attribute | | |
|---|---|---|
Performance(2) | ||
Maximum Download Speed (Mbps) | 172 Mbps | 1000 Mbps |
Maximum Upload Speed (Mbps) | 131.072 Mbps | 246 Mbps |
Ports(1) | ||
Ethernet Ports (count) (ports) | 1 ports | 4 ports |
Build & Design(2) | ||
Weight (kg) | 0.4536 kg | 1.718 kg |
Dimensions (HxWxD) (mm) | 8.7 x 6.4 x 2.0 inches mm | 9.0x2.25x8.25 inches mm |
General(2) | ||
Provider Compatibility | Time Warner Cable, Charter, Cox, Cablevision | Comcast Xfinity Internet & Voice (up to 600 Mb/s) |
Warranty (years) (years) | 1 years | 2 years |
Products in the top-left offer the best value (high score, low price).
Professional sources and manufacturer literature praise the SB6121 for its solid 4×4 DOCSIS 3.0 channel bonding, energy-efficient design, and reliable wired performance with major cable providers. However, reviewers note that the modem's DOCSIS 3.0 platform and limited channel count are insufficient for today's high-speed plans, and they recommend upgrading to a DOCSIS 3.1 model for future-proofing.
Typical users find the SB6121 easy to install and reliable for basic internet needs, especially when paired with a separate router for Wi-Fi. Common complaints revolve around its inability to keep up with faster broadband packages, the absence of built-in wireless, and concerns over refurbished units.
Professional reviewers commend the MT7711 for its straightforward, sub-15-minute installation and the value of an all-in-one modem-router-phone solution tailored to Xfinity customers.
Everyday users praise the quick plug-and-play setup, reliable Wi-Fi coverage for multiple devices, clear VoIP calls, and the savings from consolidating three devices into one. Common complaints revolve around the 600-Mbps speed ceiling, occasional activation reboots, limited 2.4 GHz range in larger homes, and the fact that the unit only works with Comcast Xfinity services.
