Motorola SURFboard SB6121
Score: 62/100
Netgear CM500
Score: 68/100Rankings
The NETGEAR CM500 is a compact DOCSIS 3.0 cable modem delivering up to 680 Mbps download and 132 Mbps upload with advanced QoS and broad ISP compatibility. Its main trade-off is the lack of built-in Wi-Fi and a single Ethernet port, limiting flexibility for higher-speed or wireless-only setups. Ideal for budget-conscious households on mid-tier cable plans that already have a separate router.
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 | 680 Mbpsbest | |
131.072 Mbps | 132 Mbpsbest | |
1 portsbest | 1 portsbest | |
| ↓ lower better | — | 18 Wbest |
| ↓ lower better | 0.454 kgbest | 0.648 kg |
1 yearsbest | 1 yearsbest |
Click an attribute name to sort · Green = best, red = worst (relative to this comparison)
| Attribute | | |
|---|---|---|
Performance(2) | ||
Maximum Download Speed (Mbps) | 172 Mbps | 680 Mbps |
Maximum Upload Speed (Mbps) | 131.072 Mbps | 132 Mbps |
Network(1) | ||
DOCSIS Standard | DOCSIS 3.0 | 3.0 |
Ports(1) | ||
WAN Port Type | Ethernet | Coaxial |
Build & Design(2) | ||
Weight (kg) | 0.4536 kg | 0.648 kg |
Dimensions (HxWxD) (mm) | 8.7 x 6.4 x 2.0 inches mm | 60x185x124 mm mm |
General(1) | ||
Provider Compatibility | Time Warner Cable, Charter, Cox, Cablevision | Xfinity, Cox, Spectrum, Cablevision |
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 consider the CM500 a reliable, entry-level DOCSIS 3.0 modem that excels on cable plans up to 600 Mbps, thanks to its 16×4 channel bonding, IPv6 support, and easy ISP activation. However, they caution that its speed ceiling and lack of Wi-Fi make it less suitable for users seeking future-proof gigabit performance.
Everyday users generally praise the CM500 for its straightforward setup, solid wired speeds for streaming and gaming, and the savings from avoiding ISP rental fees. The most common criticism centers on the absence of built-in Wi-Fi and the limitation of only one Ethernet port.
