Motorola SURFboard SB6121
Score: 62/100
Motorola MB8600
Score: 82/100Rankings
The Motorola MB8600 is a DOCSIS 3.1 cable modem delivering up to 3.8 Gbps downstream speeds and four Gigabit Ethernet ports. Its lack of built-in Wi-Fi and masked Ethernet ports limit flexibility for some users. Ideal for gigabit plans where a separate router is already in use.
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 | 3,800 Mbpsbest | |
131.072 Mbps | 800 Mbpsbest | |
1 ports | 4 portsbest | |
| ↓ lower better | — | 30 Wbest |
| ↓ lower better | 0.454 kg | 0.031 kgbest |
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 | 3800 Mbps |
Maximum Upload Speed (Mbps) | 131.072 Mbps | 800 Mbps |
Network(1) | ||
DOCSIS Standard | DOCSIS 3.0 | DOCSIS 3.1 |
Ports(1) | ||
Ethernet Ports (count) (ports) | 1 ports | 4 ports |
Build & Design(2) | ||
Weight (kg) | 0.4536 kg | 0.031 kg |
Dimensions (HxWxD) (mm) | 8.7 x 6.4 x 2.0 inches mm | 200x57x184 mm mm |
General(2) | ||
Provider Compatibility | Time Warner Cable, Charter, Cox, Cablevision | Comcast Xfinity, Cox, Charter Spectrum |
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 view the MB8600 as a solid, no-frills DOCSIS 3.1 modem that excels in raw speed potential and low-latency performance thanks to its Broadcom chipset and AQM.
Consumers generally praise the MB8600 for delivering consistent gigabit-class speeds and an easy setup with major ISPs. Common praise centers on its stability and the ability to handle multiple static IPs, while recurring complaints focus on the hidden Ethernet ports, occasional distance-related speed loss, and the need for an external router due to the absence of Wi-Fi.
“"valuable" frill-free DOCSIS 3.1 modem ideal for 1 Gbps plans”
“"Reliable high speeds (e.g., 900+ Mbps down at 20 ft in tests, stable for gigabit plans)"”
