Motorola SB6121 DOCSIS 3.0 Cable Modem

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Motorola SB6121 DOCSIS 3.0 Cable Modem
Price: $39.99
Shipping Options:: $5 Standard
Shipping Estimates: Ships in 1-2 business days (Friday, Apr 24 to Monday, Apr 27) + transit
Condition: Factory Reconditioned


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Previous Similar Sales (May not be exact model)
4/14/2015 - $42.99 (Woot-off) - Click To See Discussion (3 comments)

3/23/2015 - $42.99 (Woot Plus)

Very good reviews (4.6 out of 5.0) over at and solid reviews (4 out of 5 eggs) over at

Careful when buying these, there is an unavoidable chance that the original owner will still have their account registered to this router’s MAC address, in which case it is useless to you.

I bought one of these on Woot sale because I thought it was a good deal knowing I’d have to be switching to Comcast in a few months when I moved… I was past the 21 day return policy when I plugged it in for the first time and found out about the already registered account. Woot support refused to help. If you’re going to use it right away and are thus within the 21 day return policy, I’m sure Woot would offer a replacement or a refund (which would still be a hassle to deal with). But they did not offer me one.

Buyer beware.

Be mindful. The Black ones are refurbished. You’re going to want to use these immediately to be within the warranty period.

Also, be sure to check your bill for months after returning your rented modem. I returned mine to Comcast and ensured they removed the charge going forward. They did. However, they replaced it with an $8/month voice equipment charge. I don’t have voice service through Comcast. These crooks are rat bastards and you must watch your bill closely.

Otherwise, I’ve been very, very happy with the white version of this I wooted last summer.

Would the warranty cover that?
Warranty: 90 Day Motorola

Wouldn’t resetting the registration be required to meet the definition of refurbished, as opposed to used.

you can always file a claim in small claims court

As I have moved around the country I have ended up repeatedly buying this exact modem more than once. It is absolutely excellent. I have one now but as I am moving to France I will give it to Goodwill next week. Still, you can’t go wrong with this modem. It usually has more features than your cable service provides.

I love the one we bought a few months ago. Of course, I still had an old DOCSIS 1.0 cable modem I was renting from Time Warner at the time. Anyway, the new modem has greatly improved our speed when we have several devices connected at the same time. A genuine heartfelt thanks Woot!

Anyone know if it will work on Cablevision’s Optimum?

DOCSIS 3.0 has the potential for being faster than previous versions. Very happy w/ the 6141 I bought 2 wks ago. Beats paying TimeWarner $8 every month. Understand that you have to “activate” your new modem w/ your provider, e.g. and turn in your old modem.

Darn it I just bought the stupid-looking white one here a few weeks ago for $13 more!
Oh well - it works great and seems quite a bit faster than the one I was renting from TW for $8 a month.

I would love to buy my own modem rather than continue renting, but I have some hesitation based upon my technical ignorance and need help.

I have xfinity/comcast w/ phone, tv & high speed internet and am using their arris tg862 modem. The back of woot’s motorola modem is different from my rental in that the rental has connections for ac power, cable “in”, ethernet to my router, ethernet to my adjacent laptop and phone to my landline house phone.

Can anyone tell me if this modem will work with my current setup?

The stupid looking white one, if I remember correctly which model that was, will give you the ability to go to 300MB someday whereas this one maxes out at 150.

I bought this one instead of the white one because it saves me $8/month from Time Warner, works fine, and I am aware that in about 2 years they’ll be offering much higher speeds with DOCIS 3.1.

While I know that 150 will be completely unnecessarily fast for what I do for the next couple of years, I figure that by 2018 the 4K streaming might actually push me into wanting to get up towards 1GB. At that point I will have saved over $300 in modem rental fees for this $45 investment. I can hit up woot! for a nice DOCIS 3.1 modem and start all over again.

I have a large house that has coax in most rooms and Optimum Online. Can I use this or any other modem in addition to my existing cable modem? I will then have 2 modems on the same cable account.

I know you can add multimple Fios Moca modems, but DOCSIS w cabvle might be different.

No. You would have to sign up for a second account with Optimum.

What problem are you looking to solve?

My understanding is that it won’t work for the phone service, so probably not for you. You need a cable modem with MTA support


Thank you for your feedback.

I wish someone from Woot! could weigh-in on this matter. I would love to upgrade my system with this modem but I’ve spent the last two years in an endless conflict with Xfinity/Comcast regarding a “stolen” modem. To make it even more ridiculous, I moved to a new address and took my modem with me. I used Comcast’s smooth move, or whatever they call it, to avoid interruption in service at my new address. When I attempted to start my modem at the new address it wouldn’t work. I called Comcast and after 1 hour with a customer service expert, I was told that I was attempting to use stolen equipment. Why? Because the equipment was previously registered at another address. Guess who the previous address was…Right, it was my old address! It took another hour to get it straight but, to this day, if I ever have a problem with my Internet, the modem flags on their records as “stolen” It takes an extra hour each time to resolve the problem and get my Internet restored.
Anyway, without a guarantee that the previous registration has been wiped, I will not even consider buying a previously used modem.