Motorola MB8611 DOCSIS 3.1 Multi-Gig Cable Modem | Pairs with Any WiFi Router | Approved for Comcast Xfinity, Cox Gigablast, Spectrum | 2.5 Gbps Port | 2500 Mbps Max Internet Speeds Electronics

(10 customer reviews)


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Ultra-fast DOCSIS 3.1 performance – Delivers true Gigabit-plus speeds. Supports fast internet plans with Comcast Xfinity, Cox, and Spectrum. Backward compatible with 32×8 DOCSIS 3.0. Pairs with any WiFi router – Seamlessly compatible with any WiFi router to connect all your devices. This cable modem does NOT have a built-in wireless router or telephone call capability. Multi-gigabit Ethernet speed – A 2.5 GB Ethernet port delivers true high-speed connectivity to even the fastest routers and computers, providing downstream speeds just below 2,500 Mbps and upstream speeds up to 800 Mbps when supported by your internet service plan. Fast streaming, conferencing, gaming – Applies Active Queue Management (AQM) for reduced Internet latency and better app performance, including online gaming, conferencing, and streaming. Extreme cost savings – Owning your own modem typically saves the home $168 per year in monthly rental charges. (Savings described is for Comcast Xfinity and vary by service provider.) Built for reliability – Motorola is a worldwide leader in technology people depend on. Comes with a 2-year warranty and free support from our team of USA technicians.

SKU: B091ZHX225 Category:


Motorola MB8611 DOCSIS 3.1 Multi-Gig Cable Modem is a high-speed cable modem that supports up to 10Gbps downstream and 100Mbps upstream. This modem is perfect for home or office users who need the best performance possible. With its easy-to-use interface, Motorola MB8611 DOCSIS 3.1 Multi-Gig Cable Modem is the perfect choice for anyone looking for a high-speed cable modem.

Product Description

Motorola MB8611 DOCSIS 3.1 Multi-Gig Cable Modem

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enables ultra-fast internet

superior internet speeds while saving up to 168 dollars


Enables Ultra-Fast Internet

Featuring DOCSIS 3.1 support, the only standard that can deliver speeds over 1 Gbps/second, this modem is approved for all multi-Gigabit speed tiers by Comcast Xfinity.

Superior Tech that Pays for Itself

Eliminate monthly cable modem rental fees and save on average 168 dollars per year on your Comcast Xfinity bill. Please Note: Actual savings depend on your service provider.

Connects to Any Router

Pair with any WiFi router, including mesh or gaming routers, for shared Internet access by all your WiFi and Ethernet-capable devices.

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future proof



Easy Setup

Enjoy a straightforward setup process with just 3 connections – power, coax cable, and Ethernet.

Future Proof

Ultra-fast DOCSIS 3.1 performance with backwards compatibility to 32×8 DOCSIS 3.0.

2.5 Gbps Ethernet Port

High-speed Internet for any computer, smart TV, game station, or other ethernet-capable device.

Fastest Response Time

Featuring low latency to enhance speed and save energy for interactive games.

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Active Queue Managment

Proactive protection

two year


Active Queue Management

Significantly reduces Internet latency to provide faster page loads, streaming, and video conferencing.

Proactive Protection

Ruggedized lightning and power surge circuits protect your investment

2-Year Agreement

The MB8611 comes backed by our two-year quality agreement.

English & Spanish Support

Need Additional assistance? Our experienced, USA-based customer support specialists are here to help.

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Get the most out of your multi-gig cable modem with a gigabit WiFi router or mesh

motorola wifi 6 mesh system - 3 pack Motorola Advanced Mesh MH7602 Motorola MR2600 Gigabit traditional router MH7603 Mesh – 3 Pack (Bundle) MH7602 Mesh – 2 Pack (Bundle) MR2600 Router (Bundle) Wifi Standard WiFi 6 WiFi 6 WiFi 5 Wifi Speeds AX1800 AX1800 AC2600 Type WiFi Mesh System Wifi Router Traditional Router Motosync Smart App ✓ ✓ x Expandable ✓ ✓ x

Additional information

Item Weight

1.1 ounces



Item model number


Customer Reviews

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4.5 out of 5 stars

23,784 ratings
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4.5 out of 5 stars

Best Sellers Rank

#185 in Electronics (See Top 100 in Electronics) #1 in Computer Networking Modems

Date First Available

July 21, 2020



10 reviews for Motorola MB8611 DOCSIS 3.1 Multi-Gig Cable Modem | Pairs with Any WiFi Router | Approved for Comcast Xfinity, Cox Gigablast, Spectrum | 2.5 Gbps Port | 2500 Mbps Max Internet Speeds Electronics

  1. Greg Roberson

    I expected to have to contact Spectrum in order to register this modem and activate it. They had just pushed my speed from 200 Mbs to 300 Mbs and my old Surfboard 6141 was pushed beyond it’s capacity. I plugged my computer into the new modem and turned it on. It took about 3 minutes for it to link up and the Spectrum installation page came up. I logged in and selected New Modem and entered the MAC address. Another short wait and I was on line. Plugged the router back into the mix and everything was up and running. My download speed before the swap was 260 Mbs and after the install it jumped to 350 Mbs.

  2. Monkey Rat

    The Xfiniity compatible Modem was super easy to set-up following the Quick Start guide included in the box. Word of advice for Comcast / Xfinity subscribers — when stepping through the set-up Wizard, selecting the option to text an activation code is a joke — the code is only good for 15 minutes but I didn’t receive the text until 30 minutes had passed; just stick with your Xfinity account name for the activation and provisioning.Xfinity upgraded to DOCSIS 3.1, and, while my own 6 year old trusty Motorola Surfboard SB6580 was working fine, Xfinity found every reason to pester me about an upgrade and how much I’m missing not having a 3.1 modem lease an upgrade. I prefer to own my own modem, so, after perusing compatible modems for my region on Xfinity’s approved device page, I narrowed my choices to the ARRIS Surfboard SB8200, Netgear CM1000, and, this, the Motorola MB8600. All three are comparable at 1001 Mbps, 32 down x 8 up DOCSIS channels, and DOCSIS 3.1.All the cool kids love the Arris — especially after they ditched the very problematic Intel PUMA chipset and went with the Broadcom’s offering — and for very good reasons, it has great hardware specs. Sporting 3GB of RAM, 128MB /16 of NAND flash memory it’s a tasty treat. And, were it not a horrific white box that clashes with everything in my apartment, I’d happily have purchased it.Vanity, thy name be Monkey Rat, I know.I’ve never had a lot of love for Netgear, and, I found its hardware lacking — 128 MB of flash memory and 256 MB of RAM. Ultimately not a huge game changer, with current theoretical home speeds at 1Gb, but one would expect something a tad more, well, more from a name like Netgear. While its feature rich — which, is saying something for a cable modem — I really saw no reason to down this path.That clashing white Arris was looking tastier at this point.Then I compared the MB8600 to both and found a happy place. 512 MB of RAM and 128 MB of NAN — a buck cheaper than the Netgear with a doubling of the RAM, and while not as expensive — marginally — than the Arris, and certainly lacking a bit in the hardware department, but I paid more for future ability to bond upwards of 4 separate lines. However, the LACP technology requires a higher end router, and faster than a gig speed isn’t necessarily right around the corner, but, this device positioned nicely for a future with a potential of 4Gb.Word of caution — it’s a BIG device. If you’re familiar with the older Surfboards, this is easily double the size in height and does not come with any sort of mounting option. However, it has great ventilation thanks to a well aired grid pattern on the side.So, how does it work? My internet plan is the BLAST! 150 Mbps (stop laughing) — and i assure you, I’ve never seen that even in the dead of night — wired speeds show an increase on but it’s not really all that noticeable, whether plugged in directly to the cable modem or my ASUS RT-AC86U router, notebook and desktop performance were negligible. However, wireless performance for my nVidia SHIELD K1 tablet and Google Pixel 2 phone were significantly improved – I found this a little odd as they’re still going through a router, but, I can’t argue with results.I keep forgetting the MB8600 has a baked in spectrum analyzer utility I need to check out — I’ll add an update when I do.Ultimately, I like it — I play Everquest (the original) and noted better response times, but again, the MS aren’t earth shaking or setting the sky afire. Stream the occasional movie, and really I don’t have any complaints, and can only praise the device for its eye-popping Wi-Fi boost, for which I have no good explanation.I may change out my Cat5e for Cat6 and upgrade my router next — hopefully wringing a couple more Mbps out. But, really, I think it’s time to call xfinity and have to do some line tests. I will provide updates on that as well.

  3. Joseph N

    The modem maintains my internet at a constant speed. Now we can game and stream at the same time without any issues. It is also pretty compact. The smaller foot print allows plenty of room on the shelf for my Asus router.When you install the modem, plug it directly into the wall outlet. Once it is registered with your ISP provider, you can plug it into your battery backup.

  4. DMc

    We rented a combo modem/wifi router from Mediacom for convenience for a while. We bought this modem to replace the rental. (We already had a WiFi router to connect to this new modem.)We attached the coax to the modem, attached the modem to the ethernet port on a laptop, powered up the modem, and followed the instructions which said to go to That took us Mediacom log in page and then to Mediacom’s hardware setup page. We followed the instructions but eventually the setup failed and it prompted us to call Mediacom. I called. They verified our account and asked for the MAC address for the new modem. They need pinged it, saw it, sent a setup command to it, et voila, I could access the internet from the computer connected directly to the modem via ethernet. I then disconnected the ethernet cable from the laptop and plugged it into the WiFi router, then powered up the router, and then we had internet via WiFi throughout the house.It is suggested that you do a speed test WHILE CONNECTED DIRECTLY TO THE MODEM VIA ETHERNET to confirm that you are getting the speed that you pay for. I had to call Mediacom back to confirm our plan and they then confirmed that the modem was setup for a lower tier plan. They sent new commands immediately and then we had the speed we subscribed to. Point being, this modem is capable of speeds higher than the internet provider can deliver so if it is slow, it is likely not the modem – it’s either the setup done by the internet provider, or the wiring/signal.

  5. J. Bell

    I ordered this Motorola modem to replace an ARRIS Surfboard 6183 that I had had for 5 or 6 years. I was having to reboot the Surfboard a few times a week when my download speeds would drop to 20 or 30 (I should get over 300). Learned that was an issue with the Surfboard. Motorola is made by the same company but doesn’t have Puma chip issues (latency and jitters) that the Arris does.SO, setup (and I am NOT a techie….I’m a senior who learns by her mistakes) was easy enough. The ethernet cable that comes with the modem is VERY short. That is OK if your router is very close to your modem. In my case, my router is up HIGH on a shelf across the room from the modem, and I need a big step stool to reach it. I have a very very long ethernet chord and needed to make sure it would work (I don’t interchange things like that without asking). FORGET reaching anyone in Motorola customer service by phone. email they say they will answer within two days….I finally got through on chat support. The guy answered right away. YEP, it will work. Same category 5. I turned the modem on and everything connected except bottom LAN light kept blinking green. I hadn’t closed my CHAT with motorola so I asked that question….the man answered that was normal. Checked my speed. Where I had normally gotten around 325-350MBPS, it was 25. NOT GOOD. Motorola guy was still around and he said it was an Xfinity problem – they must not have configured it right when they activated. EEEEEE. I called and you don’t want to go through that robot voice hell if you don’t have to with Xfinity. the robot restarted the modem. Said call back in 10 minutes. I did. Robot insisted on restarting the modem again. We went through this 3 times before I got my call put through to an agent….but another robot said my wait time was over 2 hours. I put the phone to the side and managed to be 53 in line on a chat with Xfinity. I will not go into detail but THAT was a waste…the Chat guy never understood the problem….phone lady finally answered after only 45 minutes. NO issues with the MODEM she says…let’s reboot your router. STUPID ME STUPID ME. I SHOULD HAVE THOUGHT OF THAT. Reboot router so he recognizes the new kid on the block. I KNEW that…my brain was in a fog I guess. Would have saved me about 2 hours of aggravation. Rebooted. My speed was then 365 Mbps. It has held steady at more than what I pay for (Xfinity is good about that).SO, BUY this modem. Make sure your router is new enough to support it (I have a Netgear Nighthawk AC1900 that is apparently the minimum you can use but it is an amazing router). Make sure you have a compatible ethernet cable (being Category 5 seems to be the key and it is written on all cables) if you need it longer than about 6 ft. (or maybe 5 ft – it is short). I’m hoping this modem will last 5 years or so. I am a happy old lady. My hubs is happy because he can stream the golf channel without buffering. My Alexas work in every room, my light bulbs and doorbell are nicely connected and all is right with the world (or at least in my home)

  6. Mike

    Had a plan with my ISP where I was supposed to get speeds up to 300mbps and was only getting 1/10 of the speed. Turns out my modem (Motorla SB6121 Docsis 3.0) was EoL and no longer being properly supported. Purchased this modem to replace it since it was Docsis 3.1 and a bit more future proof with speeds rated up to 1Gbps. After a quick and simple with my ISP I was ready to go and getting speeds faster than rated by my isp my plan was up to 300mbps and I’m getting 350 in a speedtest result.Motorola makes great modems and are my go to when making recommendations to family and friends.*Please note this is a modem only and does not have an integrated router and you will need to buy that separate if you don’t have one in your existing network infrastructure.

  7. Scott

    I suffered for literally years with another unreliable modem that would drop internet connection dozens of times per day, run extremely hot and overheat, required regular restarts for brief stability, my previous modem to that was even worse. I have spent significant time and effort upgrading my router and a whole-home coverage with a top rated setup but still suffered. I thought I just had bad a poor connection or bad luck but got fed up and did some reading and discovered that a poor/cheap modem was a likely culprit. After finding this model and giving it a try that is indeed the case! This modem is crazy fast and stable, websites are extremely responsive now and I haven’t had it drop connection once. I consistently get near max speeds. This has literally changed my digital life and I can’t believe I suffered so long and put up with garbage modems in the past, a good modem is worth every penny and this is one of them!!

  8. Bertram28

    Received the Motorola DOCSIS 3.1 cable modem on-time from Amazon. Up and running within 15 minutes, No call to Comcast.

    Motorola Ultra Fast DOCSIS 3.1 Cable Modem, Model MB8600, plus 32×8 DOCSIS 3.0, Certified by Comcast XFINITY

    Paper instructions were in the box and also online. No firmware available for prior update. I had previously confirmed that this device is acceptable to Comcast. Before buying any network device, always check that your ISP supports the device you plan to buy. Unacceptable for us to rate an item poorly if its is not compatible with your stuff…I replaced a Cisco – Linksys model DPC3008 DOCSIS 3.0 cable modem purchased thru Amazon for $90 exactly five years ago. It has never failed. I would have paid Comcast say $10 / month to lease their inferior modem for the last 60 months, using the roughly $510 savings to enjoy Comcast “Blast” speeds not supported by their leased modem. I viewed this purchase as another future-proof, leading edge decision to replace a 5-year old $90 device. I did not expect a speed increase. Here is why.If I log into my Comcast account and search for upgrades for my Internet service, there is only a fiber option. I am maxed out at a supported wire speed of “150 mbps”. I attained that with the 5-year old DOCSIS 3.0 device. So, Comcast does not yet offer DOCSIS 3.1 service here; and, they will not reveal that to customers. I searched for a couple of hours for that revelation. The new MB8600 has a connect LED the turns blue with a 3.1 connection else stays green to confirm 3.0 per the instructions. Mine is green now. So, “NO”, Comcast has not brought DOCSIS 3.1 to my area.Follow the instructions. They work. I suggest however that you perform a broadband speed test prior to switching out your old cable modem. I also suggest you have your Comcast account number from a bill and ensure your Comcast account has your current phone number. NOT clearly said; but, I also suggest that you eliminate your network’s switches / routers / Wi-Fi and simply Ethernet connect to any one of the four gigabit Ethernet ports on the back of the MB8600. I used port one.The MB8600 synced up with Comcast quickly (according to the lights); but, I could not obtain an Internet connection. I’m guessing Windows 10 Pro simply was trying to protect me from a new intrusion. This is not a Windows 10 / Microsoft Edge issue. Solution: delete all network settings, reboot and there it was, Comcast activate. Enter your data and your MB8600 will reset. Once completed, I was online within 15 minutes. But, the speeds I had before were faster than now. Guess that my firmware had not yet been updated by Comcast.The label on the bottom of the MB8600 has an IP address, user name and password. I logged in and saw that the modem had provisioned to DOCSIS 3.0 with only one channel down and three channels up, far below its capacity in 3.0. You resolve this by pressing in the RESET button on the back of the MB8600 for several seconds till the lights flash. After, I now have 24 channels down and three channels up. I then retested my speeds to confirm that I was exceeding the Comcast Extreme 150 service level I am paying for: 180 mbps down / 24 up. That is a roughly 10% improvement still on DOCSIS 3.0. Again, Comcast here does not seem to support any faster wired speed than 150 mbps, and deeper level of DOCSIS 3.0 than 24X3 and no DOCSIS 3.1, now, no DOCSIS 3.0 32×4 either. I can hope but AOL is perceived as “high tech” here…I hate contacting Comcast customer service since I always feel as if I am training them. I may invest the day it will likely take to get Comcast to remotely re-provision my interface with them. Maybe not.Satisfied that I was connected as well as I could, I then moved on to reconnect my router for its Wi-Fi and more importantly for its added Trend Micro security not offered by the MB8600 since it is not a router, its a cable modem. My configuration is MB8600 to an Asus router with 4 gigabit ports and Wi-Fi AC2400. One wired port feeds a dumb Gigabit switch supporting five devices. A second wired port supports my Microsoft Book. I’m a retired IT guy so I avoid wireless connections excepting my cell.Yes, I have my cable modem, router and PC powered thru an uninterruptable power supply. The MB8600 documentation states that its power supply is resistant to power surges. We have afternoon storms all summer. Its fun to continue surfing while neighbors are dark; yet, my Comcast and DirecTV both work fine with a UPS power supply. Good that Motorola upgraded to some surge protection; but, I want that and sine wave continuous power. For your consideration….The MB8600 has been connected for roughly six hours. It is barely warm and only at its top. Off to a good start.UPDATE JUL2018: The MB8600 is still running like a champ. No issues. Comcast finally has some competition from Century Link with its fiber optic Gigabit offering wired into my neighborhood just days before hurricane Irma. I signed up for it since its cost was just a minor bump for gigabit from 150 mbps. A few months ago, the green DOCSIS icon turned from green to blue indicating that Comcast had turned on version 3.1 but; I was provisioned for 150 Mbps and did not see a speed jump. Nine months later, still no Century Link offer.Regardless, I opted to move to a different home. Unfortunately an older neighborhood with no Century Link fiber optic. But Comcast does offer Gigabit speed at a higher price. Comcast’s cables here are 30 to 40 years old unfortunately.I’ve been with Comcast for well more than 8 years. This was the first move / install that was completed correctly the first time. The tech clocked 960 Mbps at the MB8600 down. My PC sees less speed (580 to 870 down) with a reliable 40 Mbps up. The MB8600 performs as advertised. All 32 downstream channels and 4 upstream channels are locked.

  9. MDM

    I needed to replace my ancient Surfboard cable modem and got an Arris Surfboard SB8200 back in 2020. After 3-4 hours on the phone with Comcast/Xfinity support I plugged my old modem back in an returned the SB8200.In July, 2021 I got the Motorola MB8611 DOCSIS 3.1 and had it running at my contract speed (500 Gbps) in about 15 minutes. Now, over a year later, there have been no issues with it since then.

  10. Fixer-upper

    WARNING: THIS IS A LONG REVIEW, BUT I MAY HAVE SOME ANGLES ON THIS OTHERS DON’T :-)Wow. I really like this modem. This is a barebones rock solid dead simple workhorse. It’s got a plug for the cable and one ethernet (RJ-45) port out and I think an on/off switch.That’s it. It makes a connection. And hasn’t failed since I got it a month or so ago.All I had to do was call my ISP and give them the MAC address (on the sticker on the device)and they updated their tables and that was it. Turn it on. It goes through the startup cycle. Takes a few minutes to connect like they all do and that’s it. Set it and forget it.What prompted me to get it, is I don’t like having to rent the modem from the ISP @ $10.00/mo forever. This literally pays for itself in 16 months, and most people will have their Internet connection for many times that long, and time flies. So it’s a good investment.It doesn’t have phone connection like the ISP’s modem did. So I called the company/provider that owns copper phone lines in the area and ordered landline service. I’m a nerd/techie and don’t care what people say about landlines being for old fogeys, it’s like having a backup generator … I know I can use that landline if the power goes out or if the cell tower gets overwhelmed (too many calls or cell traffic at once), or there’s radio interference in the area. Technically cable phone is a ‘land line’ (hardwired cable connection to provider) and the battery backup in the modem (which the ISP charges more for), could give you emergency phone service in an outage, but a cable phone connection can (and does) fail for more reasons than copper wire phone service does. (Those copper wire connections are called POTS – which stands for Plain Old Telephone Service), and copper wire phones are the most reliable.Having a separate modem from a router is optima for a few of reasons… Generally hybrid units of anything do everything okay, but nothing optimally (for example combination modem-router units like my ISP rents out). Better to keep the modem separate from the router. Then you can swap either out independently to upgrade as needed, disrupting less of your own network configuration doing so, and also help avoid a single point of failure. Plus, you might be able to score a router in a pinch on shorter notice than a cable modem if the router is the component that fails. Then you can choose the router you actually like, for whatever reason, and don’t have to settle for whatever bundling du jour your ISP decides is right for you (even if it isn’t).That gets me to the other point. What DID the ISP decide was right for me (but wasn’t)?For awhile my ISP modem connection was dropping briefly in the middle of the morning. My computer came back up connected to the ISP’s ‘general public’ wi-fi connection to their router which did not work for me and I’d have to keep manually switching back to my own internal Wi-Fi LAN (network). That was not only inconvenient but it forced me to investigate was was going on there.I learned my ISP gives lets passersby connect to their rental-modem’s Wi-Fi signal, without giving me any way to disable that service! That really pissed me off to learn. The idea is that people driving around who have accounts with the provider can get internet access around the neighborhoods. If I was a passerby, that could really help me, so at first glance maybe ‘why not, be a good samaritan’.But wait! There may be more too it than that.Besides the fact that I don’t like it (for good reason), they give me no control over that ‘feature’!And I see some downsides. What’s good for the ISP isn’t necessarily optimal for me.What I don’t like about that ‘service’ is that one or more people could sit outside and suck down bandwidth (e.g. slow my connection down), unbeknownst to me. It also might cause the unit to use more energy and put out a stronger wi-fi signal than it needs to. Which health conscious people are well advised to be aware of. Wi-Fi is radiation. Not strong and may not ruin your life, but it is a stressor at a cellular level, this is known. And strong signals, persistent signals and people who are more sensitive or have immunity issues can be more vulnerable (headaches, sleep disruption, or worse). But I like Wi-Fi so I settle for whatever unknown health consequences I may not be aware of.Also it makes me wonder if a hacker might be able to use it as an additional point of access to my home network.I also wonder if it’s 100% clear to law enforcement at first glance who might be visiting sites or doing something nefarious from the connection point. Might it look like the owner is doing something that a passerby did (and even if they can sort it out later, what if it takes awhile to figure out and they make a bad assumption?)Anyway, I don’t have that problem with this modem and I’m just much happier with it all the way around.Plus it’s blazingly fast.

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