Motorola SB6121 DOCSIS 3.0 Cable Modem

Motorola's SB6121 cable modem is one of the best cable modems available on the market right now, if not THE best. It is a full DOCSIS-3.0 modem, but also fully backwards compatible with DOCSIS 2.0 and all the way back to DOCSIS 1.0. In short, it should work on any cable system. It is future-ready with IPv6 support built in.

I bought the SB6121 to replace a D-Link DCM202 which had started randomly dropping the connection several times a week, sometimes multiple times a day. Installation is trouble-free; just connect the cables and notify your cable company. (Have the MAC address from the label on the bottom of the modem handy when you call.) Many cable users report speed gains on updating to a DOCSIS 3.0 modem; I'm no exception -my download speed went from 11.5Mbps to 12.8Mbps, and my upload speed increased by 50% from 960Kbps to 1.5Mbps.

Interface-wise, there's not a lot to say. The Motorola SB6121's colored graphical-icon LED indicators are much easier to identify and read from a distance than the D-Link's closely spaced row of identical yellow-green LEDs. You can look at it from across the room and see two steady blues and one blinking amber, and know at a glance you're in good shape.

This is perhaps a more expensive modem than some, but it's worth it, and you can't fault Motorola's reputation. It also carries a better warranty than many other cable modems. Do yourself a favor and buy this OEM-packaged version; the shinier box on the retail version won't make your cable connection any faster. (But the chances are good that this modem will.)

I was wary to buy this modem from this seller because it had no reviews and it wouldn't come in retail packaging. After convincing myself that it was the same one as listed elsewhere for more, I took the plunge and have been very happy with the modem. The installation for this modem, as with all cable modems, is exceedingly easy. The sales rep at Comcast that I spoke to said that they could only guarantee me 12 Mbps service on my plan, but that I was allowed up to 20 Mbps. She said this was because I am in a high rise and that there are many tenants also using the same cable feed for Internet. I am happy to say that with this Docsis 3.0 modem, I am bonding 4 channels and getting over 22 Mbps down and over 4 Mpbs up which is plenty for a vacation spot. I highly recommend this modem and you shouldn't hesitate to buy it here and save a couple bucks.

Buy Motorola SB6121 DOCSIS 3.0 Cable Modem Now

I decided to buy my own modem instead of renting the lower-end model from Comcast for $7/month. This has DOCSIS 3.0, so it supports higher speeds than the DOCSIS 2.0 Comcast rented me. My speeds increased from 18Mbps to 24Mbps by just installing the new modem. I just called Comcast, gave them the model # and serial/MAC, and they set it up over the phone. The seller shipped the item very quickly too!

Read Best Reviews of Motorola SB6121 DOCSIS 3.0 Cable Modem Here

I am using the SB6121 cable modem with Comcast cable. Setup was fast and easy. Plugged in the box in place of the old one, and called Comcast. The service representative knew what he was doing. It took about 20 min from when I called to everything working properly (including hold time). Make sure to have the MAC address handy when you call. For this packaging, the MAC is on the sticker on the bottom of the unit, as well as inside the cardboard packaging on the stickers on a paper strip.

The indicators on the box are great. The receive and transmit indicators are bright blue if it detects a docsis 3.0 connection, green if it detects a docsis 2.0 connection. These receive, transmit, and online indicators are steady if connected properly. Very easy to know the status at a glance from across the room. A note: On initial powerup (before calling Comcast), the receive / transmit light settled on green, and that had me wondering what was going on. It turns out that Comcast had to get the correct profile downloaded on the box, and the right configuration setup at their end before the indicators are meaningful.

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After 2 days of use with Comcast, my new Motorola suddenly stopped connecting to the Internet. After some time on the phone with Comcast tech support, we found that the modem was actually registered on multiple accounts, meaning that the "new official manufacturer brown box" covers up for the fact that the seller sells used merchandise which, at least in my case, is not carefully reset before resale. I thought it came from Amazon but it's actually a 3rd party.

Buyer beware. Great modem, bad seller.

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