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ARRIS / Motorola SB6121 SURFboard Cable Modem Review

Motorola's SB6121 Cable Modem offers excellent performance at an affordable price.

Get The Best Price On A Motorola SB6121 Cable Modem

If you're currently subscribing to a cable service provider, chances are you're probably paying a premium fee to rent a cable modem each month without not even realizing it. The problem with this situation is that you're likely renting an entry-level modem and overpaying largely for its use, typically to the tune of $6-$10 per month. The trick to getting around this is purchasing your own modem which will run anywhere from $25-$130 depending on the model. However, if you do the math, this route will pay for itself over a few months and you'll be able to enjoy the increased performance and speeds that comes with a better modem.

In this review, we are going to take an in-depth look at the ARRIS / Motorola SB6121 SURFboard DOCSIS 3.0 Cable Modem which currently sells for $69.99 via Amazon. This model falls into the mid to high-end modem category as it offers excellent performance although it lacks the bells and whistles in some of the higher-priced models such as built-in Wi-Fi support and extra Gigabit Ethernet ports. Due to this, you'll want to couple this modem with a router to extend your Internet access to multiple devices.

Included in the box is the SB6121 modem, a brief instructions packet, an Ethernet cable, and a power cable. The modem itself is a relatively slim black box that is designed to stood upright. The front of the modem has a small Motorola logo at the top followed by an array of LED lights which provide realtime indications of your modem's status when in use. The rear of the modem offers one Ethernet port (ideally used to connect to your router) as well as the power input and coaxial jack.

The modem casing itself is made of a reflective black plastic material which does feel rather cheap. On the other hand, the modem is only meant to be sit stationary so it should not be much of a problem in the future. The slim, upright design is convenient for desk top placement as it doesn't take up much space and can be easily kept out of the way.

As for features, the Motorola SB6121 offers the updated DOCSIS 3.0 technology. This makes it capable of pushing out download speeds of up to 172 Mbps and upload speeds up to 131 Mbps. Like I stated earlier, it only has one Ethernet port and no built-in Wi-Fi support so you'll want to combine this modem with a router to get the best bang for your buck. If you'd rather simplify this and just buy a modem/router all-in-one then you could go with the Motorola SBG6580 DOCSIS 3.0 Wireless N Cable Modem which expands upon the SB6121 since it offers built-in dual-band Wi-Fi capabilities and harnesses 4 integrated Gigabit Ethernet ports.

Depending on which Internet provider you subscribe to, you'll need to notify them to let them know that you are going to use your own cable modem. For example, I am a Time Warner Cable subscriber so the process entailed a simple 5 minute phone call to their customer support to give them the MAC address of the modem which they put in their system activate my modem on my account. If you skip this step, there is a very good chance your Internet will not work after hooking up this modem, that is until you contact your Internet provider and have them enable it for your account.

I use Time Warner's highest Internet plan which advertises speeds of 50Mbps down and 5Mbps up. As you can see from my Speedtest results below, this modem coupled with NETGEAR's Nighthawk R7000 router is performing exceptionally well. Prior to switching to this modem, I was utilizing Time Warner's rental modem which resulted in a fair share of Internet hiccups and speed bottlenecks on a regular basis. After switching to Motorola's SB6121 modem, there has been a significant change in increased reliability of my network and a slight yet noticeable increase in my overall speed Internet speeds.


In the end, I'm very satisfied with my purchase of the ARRIS / Motorola SB6121 SURFboard DOCSIS 3.0 Cable Modem. It has greatly improved the reliability of my home network and I have also seen a noticeable speed increase. While it lacks the advanced features like built-in Wi-Fi or a plethora of Ethernet ports found within the Motorola SBG6580, it gets the job done when coupled with a decent router which is exactly its purpose. If you're tired of paying the outrageous modem rental fees that your cable provider charges you each month, investing in your own cable modem like the Motorola SB6121 is a very wise decision.