A new and improved version of the world's most widely deployed DOCSIS cable modems. For the residential cable subscriber who wants a powerful modem capable of delivering a high-speed data service at blazing fast speeds.
- Up to 160 Mbps downstream, up to 120 Mbps upstream
- Front panel, easy to read operational LEDs to indicate status and simplify troubleshooting
- IPV6 support - latest Internet communication protocol
- Rear panel color coded for ease of installation
Motorola SB6121 SURFboard DOCSIS 3.0 Cable Modem
Motorola SB6121 SURFboard DOCSIS 3.0 Cable Modem Reviews
319 of 325 people found the following review helpful:
Stay with the SB6120,
The SB6121 is a little smaller than the SB6120 but runs much warmer than the SB6120. Looks like they tried to cram too much hardware into too small of a space.
My SB6121 did not come with the power save button (it's listed as an optional feature), so about the only difference between the two models is the design. Both the SB6120 and the SB6121 use the same firmware: labeled SB612X.
So unless you want the different looking LED lights and a smaller and warmer box for a higher price, stay with the SB6120.
As far as speeds are concerned: the multiple channel bonding on these DOCSIS 3.0 modems is nice for sustained constant speeds. It also makes it easier for your ISP to enforce the speed cap if they choose to do so (Comcast in my case does). I was getting 20+ Mbps down and 3+ Mbps up on my old Linksys DOCSIS 2.0 modem, however that was the... Read more
85 of 86 people found the following review helpful:
Does the job well/tip for Comcast users,
Amazon Verified Purchase
This review is from: Motorola SB6121 SURFboard DOCSIS 3.0 Cable Modem (Personal Computers)Out of nowhere, I was having excruciatingly slow internet speed on Comcast. The Comcast tech advised that my Motorola SB 4100 was at the "end of life" and that I should upgrade. Skeptical, I purchased this modem which is a DOCSIS 3.0 (and backwards compatible) modem. It worked. I went from a 2mbps download speed to over 17mbps. What a difference. There was one installation glitch that you need to be aware of. When you hook up the modem (connect the coax cable, connect the ethernet cable, and plug it in, that's it), and then try to get online, it will direct you to a Comcast self-activation screen (no other site is available). After entering my account number and phone number and hitting the "next" button, I got a blank screen, and nothing happens. So I called Comcast and they said that usually happens if you are doing an upgrade; it mostly works only for a new service connection. However, it is a simple matter to give the tech your MAC address and the serial number. After... Read more
96 of 104 people found the following review helpful:
Great Modem works with Comcast,
Amazon Verified PurchaseBottom line: this is a great modem and it works with Comcast. Comcast just doesn't have its act together. This modem is not only on their approved list, it has a three star rating, which, according to Comcast, is "the highest and most thorough level of testing." When the cable installer got here (I got a new line installed), he said that this modem was NOT on the Comcast list. Since I still had my DSL line working, I showed him that not only did Comcast approve the modem but that Comcast thoroughly tested it. He had to call the "office" to activate the internet service. The "office" didn't want to set up internet service for this modem; the "office" stated that this wasn't an approved modem. Well, he recalled the "office" and got someone else and they set up the service. I've been happy ever since. I'm supposed to get up to 20 Mbps download and 4 Mbps upload. My computers are connected wirelessly. Speednet states that I am getting 20 to 25 Mbps downloads and the upload... Read more
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