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Customer Reviews

4.3 out of 5 stars
22,302
Capacity: Download Speed: 343 Mbps|Model: Cable Modem|Change
Price:$68.75+ Free shipping with Amazon Prime
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on January 12, 2013
Swapped out my Comcast rental modem, was up and running in just a few minutes, and now I don't have to pay the $7 modem rental fee to Comcast. I'm provisioned for the 105/20 Mbps package and typically get 120/20.5 Mbps.

This modem can utilize up to 8 channels of downstream for a theoretical max speed of 343 Mbps whereas the Motorola SB6121 and other earlier/cheaper DOCSIS 3 modems can only utilize 4 channels maxing your download speeds out at 172 Mbps. Just something to think about if you plan on using this modem for a few years as speeds offered will inevitably increase.

Also, it *does* support IPv6 even though Comcast's page doesn't list it as certified yet. Motorola's data sheet specifically lists the SB6141 as IPv6 ready and tests with an Apple AirPort Extreme (v7.6.4) and MacBook Pro running 10.9 confirm this.

Update 2/4/13: Still working great without issue.
Update 3/25/13: Still not even a single reboot required.
Update 8/28/13: Still working great...
Update 7/8/14: First issue... had an outage for 15 min. Reset the modem and it didn't resolve the issue. Called Comcast, they reset something on their end and I was up and running again. First issue since I bought it.
Update 4/5/2015: Comcast recently upgraded my speed tier and I'm consistently getting speeds up to 180/25 Mbps.
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on September 29, 2011
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 about 5 minutes, while he stayed on the line, it came alive, no problem. BUT, here's the thing: the serial number they need is the CUSTOMER serial number. This is only found on the bottom of the Motorola box the modem came in. This is different from the "S/N" serial number that is on the label that is on the instruction sheet and on the bottom of the modem itself. The customer S/N has letters in it; the regular S/N has only numbers in it and is too long. My first Comcast tech didn't know that and it took a day to sort it out. Other than that, it works well with my iMac and Apple Airport Extreme Base wireless router. Enjoy
9191 comments| 2,799 people found this helpful. Was this review helpful to you?YesNoReport abuse
on April 17, 2013
I purchased this SB6141 to replace my VERY old Linksys DOCSIS 1.0 modem. I recently upgraded to 75mb download from RCN (Chicago) and DOCSIS 1.0 was going to bottleneck my speed.

The modem (as are all modems) was extremely easy to install. Plug in, call ISP and you are good. The speeds are fantastically fast and this modem was well worth the price.

****I purchased this white SB6141 over the black SB6141 for one main reason. If you do your research you will notice that the Black SB6141 are only issued to ISP's from Motorola. Meaning, if you purchase a black model from Amazon (or any store), you are purchasing a used or refurbished product (they also ship in ordinary brown cardboard boxes). The only consumer model of the SB6141 is the white model which ships in traditional packaging. The white model is THE ONLY model that comes with a warranty from Motorola. I know this because I called Motorola twice and spoke to two (2) different reps who said the same thing; "Black boxes are for ISP's and do not have a warranty while the white boxes are for consumers and come with a warranty". Further complicating matters is that the black SB6141's usually have old firmware on them because they were generally made a few years ago. White SB6141 have newer or the newest firmware because they are shipping directly from the manufacturer. Your ISP may or may not flash customer owned modems to the newest firmware. If you purchase the Black model, you might be purchasing a 3 year old modem with no chance of upgrading it (also remember that you cannot flash your own modem's firmware).

Do yourself a favor and research this white consumer model over the black ISP model before you pull the trigger. I spent 20 bucks more for the white SB6141 so I could have peace of mind and I would strongly encourage you to do the same.*****

The only "con" I have about this modem is that the blue lights on the modem ARE BRIGHT AS @#%&$. Seriously, at night, my living room is glowing blue from the lights. I really cannot express enough how bright the lights are. You were warned.
3636 comments| 1,560 people found this helpful. Was this review helpful to you?YesNoReport abuse
on May 27, 2013
Tired of paying my ISP to rent one of their modems.

Lots of research and this one just kept coming up on top for me; reliable manufacturer, good reviews by others, ease of setup, built for the future with 8-up 4-down bonding. Works just like promised with never a hitch. My only complaint is, as others have mentioned, the lights are irritatingly bright; this I solved by mounting under my desk where it is out of sight.

TIP 1: Make sure you purchase this "Retail Packaging - White". Don't try to save the few bucks buying the black version; all my research shows they are refurbished rentals from ISP providers and the common complaint is that they stop working about the time the warranty expires.
TIP 2: Make sure your ISP supports the firmware. My cable company does not specifically show this model but it supports the same model two generations back - close enough. All I did was a Google search " modems supported by mediacom des moines" (my ISP, my city). Take the time to do your research. I did and I'm VERY happy (except for the irritating lights).
TIP 3: One mis-notion: Just because this modem is "state-of-the-art" for home use, don't expect speed increases just by swapping modems. (Though my wife and I swear our pages load faster even though speed tests show the same up/down rates as before.) You have to up your internet package (dollars) to do this.

One month update - as pleased today as the day I set it up. Never a bump or a glitch.

Eight months and I'm as happy as the day I set it up!

A year and a half - I'm still as happy as the day I set it up!
1919 comments| 973 people found this helpful. Was this review helpful to you?YesNoReport abuse
on February 4, 2012
I felt compelled to write this to help those who will encounter the problems I faced (and mentioned here). I'm one of the many people who wanted to avoid renting a modem from Comcast and bought this modem based on the stellar reviews, only to find that on the day of installation/activation that it "didn't work". Didn't work meant experiencing the same symptoms that's been mentioned here several times - "modem connects but then resets/power cycles/disconnects itself within a few minutes." This happened to me on the day I activated my Comcast internet. The technician spent 1.5 hours trying to figure it out and ended up loaning me a Comcast modem (Motorola SB5120 DOCSIS2), which came up almost instantly and activated just as fast (go figure). He suggested I return this modem as it was defective, in his opinion. I didn't like this since the probability of this was very small. But I saw what I saw and could not get past the first page of Comcast self activation screen with this modem. Before the web page for self activation could proceed, after typing my account info and phone number, the modem would conveniently lose connection. At one point I did get to the next screen where it was scanning for devices, but the modem cut out thereby hanging the process. The modem was packed up in the box for return to Amazon when I couldn't shake how much this bothered me and by my bad luck. So I came back here and read pretty much every review. What I found was there's several people who experienced the EXACT same symptoms while trying several of the same modem. There were two reviews that stood out. One was from a person who mentioned the Comcast technician moaned when he saw it was this modem, indicating that the technician was aware of difficulties using this modem. The person mentioned that after 70 minutes of trying to get the modem to connect the technician advised him to leave the modem powered on and hooked up for awhile and to try activating later. The person did this and was successful in activating the modem. The other review was from a person who was admirably persistent. His review talks of several attempts to connect and refusal to accept that the modem was defective. He ended up leaving the modem power on and connected overnight so the modem could "download firmware". The next day he was able to activate after two attempts with Comcast self activation process. Lastly, I noticed for me that if I left the modem power on and connected but make no attempt to activate it via Comcast web site, the modem retains connection (via indicator lights) for prolonged periods of time. It only seems to lose connection when I try to activate. Based on this I felt something was broken with Comcast activation process specifically for this modem or perhaps Comcast was intentionally making it difficult to activate this modem to convince customers to rent a "reliable" modem from them. To be honest, it almost worked for me. After sitting there watching the technician agonize trying to get the modem to work, I was tempted to rent the modem and move on with life. So as one last hail Mary attempt, this is what I did:
1. Took the modem back out of the box and left the Motorola SB6121 power on and connected to cable outlet overnight just to entertain the possibility that some firmware or info needed to be downloaded to the modem and that for some reason it took a long time to do so.
2. The next morning I tried Comcast's self activation process.
3. Every time Win7's network icon in the lower right corner of my screen indicated that a internet connection was established (vs. exclamation mark) I immediately opened a IE windows and started the activation process with my account and phone #. The modem still lost connection when I did this but I kept on trying.
4. It took me about 4 tries to SUCCEED. Each time I tried, I started back on the account and phone # page. But each time it got further and further in the activation process.

Attempt #1: Account/phone # screen -> Retrieving Device Information -> Modem lost connection.
Attempt #2: Account/phone # screen -> Retrieving Device Information -> List of devices detected (screen showed my MOTR SB6121 modem and a DTV box both shown as "inactive" -> Modem lost connection. (A thing to note here is that Comcast's activation system could specifically identify this modem. This meant it was in their system and their system was able to communicate with it)
Attempt #3: Account/phone # screen -> Retrieving Device Information -> Listing devices detected -> Clicked "Rescan" device (modem)-> Hit "Next" to activate then got to screen where it said "Activating Device - This may take 10 minutes" -> Modem lost connection
Attempt #4: This isn't a real attempt because all I did is leave the web browser in the previous "Activating Device" screen and waited for the modem to re-establish connection again. I stepped away for a few minutes and when I came back I got a screen that stated "Device Activate" (and some other instructions that didn't matter) Hallelujah! Also note, NO phone calls had to be made to Comcast to activate this modem.

At this point, this modem which was losing connection all the time before, now had a seemingly rock solid connection!!! I'm using the connection now with this modem as I type this. I've did some basic testing, streamed video, surf the net,etc. NO LOSS OF CONNECTION! I did a speed test and I'm getting 25Mbps down and 3.8Mbps up.

Based on my experience so far, it is in my opinion that this modem works and is as good as what the majority of the reviewers here have stated. The problem lies in Comcast's self activation process which is suspicious. What doesn't make sense to me is the fact that modem can hold a solid connection if you didn't attempt to activate and after it's successfully activated. It was only when I tried to go through the self activate process that I saw problems. I can't say much about whether step #1 helped but it can't hurt to try. I mentioned it only to inform people of what exactly I did.

I truly hope this helps people. Amazon is top notch. This modem is now doing what it's suppose to do with no issues. I'll come back and update this review in about a month to report if it still holds true. I think it will but we'll see. And lastly, thanks for the people who shared their experiences here. If it weren't for them I would have returned the modem back to Amazon and go through the hassle of finding another modem or giving in and renting one from Comcast. I'm trying to pay it forward with this review.
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on March 17, 2012
... It seems that various ISPs are breaking FCC regulations and Federal Law by refusing to activate some newer modems, in an attempt to force users to use a "leased" modem.

There is an essentially IDENTICAL version of this device, the SB6141, which is the "ISP leased" version of this. You can't buy that, at least not "officially," mind you.

(EDIT - since I originally wrote this, it does seem that it's become possible to buy the "cable operator only" SB6141 directly...)

Time Warner Cable has just had me on the "loop" for the past two and a half hours, and I'm still on hold as I write this. They're telling me that the device isn't on the "approved list" and thus cannot be activated on their system. This, of course, is PATENT NONSENSE. All they require in order to access any device is (a) a device which speaks the same electronic "language" (in this case, DOCSIS 3.0, which TWC Austin supports fully, and brags about supporting fully), and (b) a valid, unique HFC MAC ID code.

The MAC ID is what allows the two devices (the ISP's "source" modem and your modem) to talk to each other, as the ISP needs to know that the ID it's talking to is an ID which it's supposed to talk to, and they need to speak the same language. THAT IS ALL THAT IS REQUIRED ON ANY TECHNICAL BASIS WHATSOEVER.

It is a violation of Federal Law and FCC regulations for an ISP to refuse to service any device which has a valid, unique, and "not stolen" MAC ID and which uses an approved communications protocol.

Those of you who have been told "Comcast won't support this" or, as I just was, "Time Warner won't support this," please realize, YOU ARE BEING ROBBED, every bit as much as if they put a gun to your head and told you to hand over your wallet. It is a CRIME for them to do this.

I am currently on hold, with a "customer advocate" at Time Warner, attempting to get my personally-owned, legally-required-to-be-supported device added to my account.

******

Okay, after a long dialog where I quoted letter and verse of Federal law to the "advocate," I got them to add my modem to my account. And it's working flawlessly.

I would not ordinarily post things not SPECIFICALLY about the device on a review of the device, but in this case, I felt like it was necessary, as some folks may believe they've got a defective piece of hardware (based upon what the ISP tells them) when this is NOT the case.

My ping times have improved... which is somewhat surprising to me, honestly... from about 58ms to around 20ms. I'm not sure why that's the case, but it's a good indication that I have a better connection (lower ping times means less delay between when you send something at one end and when it's received at the other end, basically). My throughput is much more consistent and level, and I haven't seen any of the disconnection errors I've seen repeatedly with my older (DOCSIS 1.0) modem. It seems to be performing flawlessly.

If you have an internet service provider (ISP) who has support for DOCSIS 3.0 (the latest iteration of the modem-interaction-language standard), this is a great choice. Just be prepared to have to argue a bit with your ISP, who seem, in many cases, to be doing everything possible to get you to lease one from them instead of buying your own. Once they give in and agree to activate the MAC code on their system, this will work just fine on ANY current ISP, and will provide full DOCSIS 3.0 support on any DOCSIS 3.0-supporting network.

Don't let the script-reading "support" types tell you otherwise.
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on January 12, 2013
after I tried and failed attempt to buy this modem from amazon (its ok amazon made up for it) I ended up buying it from another website. it works great. movie streaming is great.

1 important thing I have figured out is that if you use TWC they will try to sneak you. they will peg your speed at 10mb until you notice it and contact them then they will say everything looks normal on their end and you test your speed again and its fine or they blame your modem. when they fix the issue they will leave it for a day or 2 and limit your speed again. they do this because you used your own modem and not theirs. they will try to blame the modem but it magically starts working right when you call them out on it. they do this for 2 reasons. 1) so you don't notice they lowered your cap and when streaming movies or games are not working right they try to blame your modem and talk you into renting theirs. 2) so they can talk you into upgrading service with the new rented modem that they try to stick you with because your modem is "bad". I am not the only 1 that this has happened to in my area and suspect it is happening in other TWC areas too since the service itself isn't "area" controlled. if you have had this happen to you called them out on it and tell them you know what they are doing and will contact the BBB and FTC if it happens again. if this has happened to you please post a response to my review with at least "I" or "me too" I want to get a count of how many have had this happen by TWC.

like I said the modem itself is awesome. best modem I have ever had period.
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on October 16, 2013
hey, amazonians! i got this because i read the other reviews that it works with comcast. unfortunately, comcast doesn't know that it works with comcast - are you surprised? i called and was on the phone for more than an hour while the tech tried to enter in all the information over the phone. they said i needed to bring it into a comcast location to get it manually entered - shut the front door. i asked for a supervisor who also knew nothing. i heard munching on popcorn in the background. whatevs.

i disconnected my old modem and plugged this one in. i waited until i saw all the pretty lights and then went back to my computer and tried to open a website. the browser automatically directs you to the comcast activation page. log in and follow all the simple instructions. the page will auto-detect your modem and then activate it. you just press the easy button and wait a few minutes. you never have to talk to a meatbag attached to a phone line. set it and forget it. in a few minutes it's done and you're connected.

sorry i had to learn this the difficult way. hopefully this process will be easy for you.
nice shiny modem with flashy lights. nice internet connection.

sb6141 - 5 stars for ease of use and sweet lights.
comcast - 0 starts because you always get 0 stars.
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on July 8, 2011
I have tried both the SB6120 and the SB6121 and the signal levels and speeds were the same on both.
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 peak when the transfer first started, then it would taper off.
The DOCSIS 3.0 modem stays right at the 12/2 ceiling of my speed tier, but at least the speeds stay right up there and do not drop off after a few seconds.
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on May 7, 2013
I purchased this MOTOROLA SB6141 SURFboard modem after receiving a notice from Comcast that I should upgrade my modem to DOCSIS 3.0. I purchased this more expensive white color one instead of the less expensive black color one (of the same model number) after hearing that some black ones were not really new, but had been used by carriers.

Anyway, this modem works for Comcast. Activation took about ten minutes with a call to 877-266-2678 (Comcast tech support). With my five-year-old DOCSIS 2.0 RCA modem, Speedtest.net test reported 16.4 Mbps download speed, 0.21 Mbps upload. With this new DOCSIS 3.0 modem, the download speed has been doubled to 38.77 Mbps (but the upload speed is the same).

Update (one week later): the modem still works well, never stopping or flipping. The download speed tested via Speedtest.net and via a wired connection is still pretty good, ranging between 30 (5-10-2013) to 40 Mbps (5-9-2013). The upload speed, though, remains 0.21 Mbps on each testing.

One user asks if he can use this modem with Comcast phone service. I think not. I believe that will require a different modem with telephony. Check Comcast site for the devices with phone feature: [...]. Personally, I use Ooma gadget (Amazon also carries it) to work along with this modem. Other modems will also work with Ooma. As long as you have the Internet working, Ooma will get you all the phone features you want at a much lower rate (basic rate is less than $10). I have been using Ooma for five years now, and it works well.

2nd Update (after speaking to Comcast tech): As my low upload speed (0.21 Mbps) caused my outgoing email with attachment to halt a long time, I gave Comcast support a call. They manually entered my MAC ID into their system, and had me reboot the modem AND the router. That really made a big difference, I am getting a download speed of close to 50 Mpbs, and an upload speed of 11 Mbps (vs 0.21 Mbps). Big help from the Comcast tech! (My Comcast Internet service is "Blast" or "Performance", with "Powerboost".) So all is really good now.

3rd update (one month): the modem still works without any issues. Speedtest.net tests reported download speeds around 60 (Mbps), but upload speeds ranged from 11 (5-12-2013) to 0.97 (6-1-2013), even after powering off and on both the modem and the router. I assume that it was the carrier (Comcast) who is to blame, not the SB6141 modem.

4th update (almost two years after the purchase): For about five months now, I am enjoying a super fast download speed of over 120 Mbps and an upload speed of over 12 Mpbs. With the same modem, same carrier (Comcast). Comcast has upgraded their speed in certain areas, and I received a notice to that affect. I only needed to reboot my modem once, and instantly saw my download speed jumped from 50 Mbps to over 120 Mbps.
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