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NETGEAR Cable Modem CM400 Compatible with Cable Providers Xfinity by Comcast, Spectrum, Cox | For Cable Plans Up to 100 Mbps | DOCSIS3.0, Black (CM400-100NAS)


$65.99 $3.59 per oz
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Purchase options and add-ons

Brand NETGEAR
Internet service provider spectrum, optimum, cox, xfinity
Connectivity Technology Wireless
Total Ethernet Ports 1
Color Black

About this item

  • ELIMINATE MONTHLY CABLE MODEM RENTAL FEES - Up to $156 per year
  • DOCSIS 3. 0 Cable Modem with 1 Gigabit Ethernet port. One (1) Gigabit Ethernet port with auto-sensing technology
  • Up to 340Mbps download and upload speed. Separate router required for WiFi. 8x4 channel bonding.
  • DOCSIS 3. 0 unleashes 8x faster download speeds than DOCSIS 2. 0
  • Ideal for streaming HD videos, faster downloads, and high-speed online gaming
  • Required for the fastest cable Internet speed tiers
  • Compatible with Xfinity from Comcast, Spectrum, Cox, & more. Not compatible with bundled voice services.
  • Memory storage capacity: 64.0 MB

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This item: NETGEAR Cable Modem CM400 Compatible with Cable Providers Xfinity by Comcast, Spectrum, Cox | For Cable Plans Up to 100 Mbps | DOCSIS3.0, Black (CM400-100NAS)
$65.99 ($3.59/oz)
Get it as soon as Wednesday, Jul 31
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NETGEAR Cable Modem CM400 Compatible with Cable Providers Xfinity by Comcast, Spectrum, Cox | For Cable Plans Up to 100 Mbps | DOCSIS3.0, Black (CM400-100NAS)
NETGEAR Cable Modem CM400 Compatible with Cable Providers Xfinity by Comcast, Spectrum, Cox | For Cable Plans Up to 100 Mbps | DOCSIS3.0, Black (CM400-100NAS)
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ARRIS Surfboard S33 DOCSIS 3.1 Multi-Gigabit Cable Modem | Approved for Comcast Xfinity, Cox, Spectrum & More | 1 & 2.5 Gbps Ports | 2.5 Gbps Max Internet Speeds | 4 OFDM Channels | 2 Year Warranty
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Price$65.99$99.99-46% $34.95
New Price:$64.99
-20% $183.99
List:$229.99
$199.99-11% $196.45
List:$219.99
Delivery
Get it as soon as Wednesday, Jul 31
Get it as soon as Tuesday, Jul 30
Get it Jul 31 - Aug 2
Get it as soon as Tuesday, Jul 30
Customer Ratings
Easy to install
4.0
4.4
4.2
4.3
4.4
4.2
WiFi signal
3.5
3.9
3.6
3.8
4.1
3.7
Tech Support
3.1
3.1
2.9
3.4
3.6
3.0
Value for money
2.0
4.3
4.0
4.0
3.8
Sold By
Flipsters
Hitron Americas
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Amazon.com
SupplierX
Fba Sales
connectivity tech
Wireless
Ethernet
Ethernet
Ethernet
Ethernet, Wi-Fi
Ethernet
ethernet ports
1
2
1
1
2
2
number of ports
3
2
1
1
2
data transfer rate
340 megabits per second
1 gigabits per second
1000 megabits per second
300 megabits per second
2500 megabits per second
max downstream rate
343 megabits per second
1000 megabits per second
960 megabits per second
1029 megabits per second
1 gigabits per second
2500 megabits per second
max upstream rate
123 megabits per second
350 megabits per second
960 megabits per second
246 megabits per second
2.5 gigabits per second
modem type
cable
cable
cable
cable
dsl
cable

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    Product Warranty: For warranty information about this product, please click here. [PDF ]

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    NETGEAR Cable Modem CM400 Compatible with Cable Providers Xfinity by Comcast, Spectrum, Cox | For Cable Plans Up to 100 Mbps | DOCSIS3.0, Black (CM400-100NAS)


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    Product Description

    The NETGEAR CM400 High Speed Cable Modem provides a connection to high-speed cable Internet, up to 340Mbps. It is Cable Labs certified and with DOCSIS 3. 0 is 8X faster than 2. 0. It is compatible with U. S. cable Internet providers like Cablevision, Cox, Time Warner Cable, XFINITY & more.

    Customer reviews

    4.1 out of 5 stars
    4.1 out of 5
    1,656 global ratings

    Customers say

    Customers like the performance, ease of setup, value, and signal strength of the modem. For example, they mention it works extremely well, is easy to connect to a separate wireless router, and is great for the money. That said, some complain about connectivity and heating. Opinions are mixed on speed and quality.

    AI-generated from the text of customer reviews

    251 customers mention "Performance"177 positive74 negative

    Customers like the performance of the modem. They say it works extremely well, has done the job admirably, and plays nicely with their router. Some mention that the initial performance was pretty good, showing a solid 160mbps down. They also say that it works very well for connection to Comcast Xfinity internet service and that it gets full signal no issue.

    "Greate ,Cheap , easy to set up , and works perfect !..." Read more

    "this modem is really my new favorite. works extremely well, no lag, no internet connection problems like my previous arris which was not good...." Read more

    "...It loses connection and will sit idly for a few minutes before it decides to pickup again, or until I manually reset it...." Read more

    "...Works great, set it up its pretty easy , just call your cable company to register the ESN and that's it ...." Read more

    96 customers mention "Ease of setup"90 positive6 negative

    Customers find the setup of the modem to be easy. They mention that the instructions are clear, and the setup process is simple. Some say that the mode is small, making it not an eyesore. Overall, most are satisfied with the ease of setup.

    "...It was good deal i couldn't pass up ! It connected cox internet service perfectly - Has normal modem issues that you normally expect once in a blue..." Read more

    "...was really easy to set up and had all the information on how to install to my charter account...." Read more

    "...Works great, set it up its pretty easy , just call your cable company to register the ESN and that's it ...." Read more

    "...Nice Design, Matches the rest of my Netgear equipment.Easy to setup.Clear instruction manual.Lowered my monthly internet bill...." Read more

    81 customers mention "Value"69 positive12 negative

    Customers like the value of the modem. They say it works great, is relatively cheap, and saves them serious cash. Some mention that it reduces their monthly internet bill.

    "Greate ,Cheap , easy to set up , and works perfect !..." Read more

    "...Easy to setup.Clear instruction manual.Lowered my monthly internet bill...." Read more

    "Bought a second one of for my parents. It's cheap and it does the job...." Read more

    "...searching I found my self purchasing this product because of it's affordable price and the fact that it has a wireless router built in...." Read more

    52 customers mention "Signal strength"37 positive15 negative

    Customers like the signal strength of the modem. They mention it's fantastic, easy to install, operate, and understand. They say it works great for 25 Gig internet from Comcast, works great with xfinity 100Mbs service, and is perfect for cable downloading to give wireless access throughout the house.

    "Greate ,Cheap , easy to set up , and works perfect !Perfect modem if you use Internet on your ps4 or phone and want a stonger connection..." Read more

    "...based on condition my modem came in and the fact that it works for Comcast Xfinity internet." Read more

    "...but only one computer could be on line at a time, and then it kept dropping the signal...." Read more

    "In terms of internet quality the device is great...." Read more

    60 customers mention "Speed"28 positive32 negative

    Customers are mixed about the speed of the modem. Some mention that it's great and allows them to stream Netflix and play online, while others say that it is too slow and unable to provide the high speed internet that they are paying for.

    "My Unite lasted me for about 3 years before it started slowing down my internet speed. The main reason was heating...." Read more

    "this modem is really my new favorite. works extremely well, no lag, no internet connection problems like my previous arris which was not good...." Read more

    "...chipset has a known issue for causing "buffer bloat", which can result in high latency...." Read more

    "...It started out fine, easy to install and ready to go in minutes. Over time however it has started dropping internet connections...." Read more

    47 customers mention "Quality"15 positive32 negative

    Customers are mixed about the quality of the modem. Some mention it's a solid product with a decent life cycle, very reliable, and excellent quality. However, others say that it only lasted one week, frequently crashes, and failed all expectations.

    "...It usually works ok, but at night it seems to struggle." Read more

    "...that lasted one month beyond it's warranty date... This one only lasted one month, so I'm replacing it with another of the same...." Read more

    "...60;(' The CM400 is a very reliable and sound unit. Bought April 2017, over a year of quality service." Read more

    "...This did NOT last long. I was looking at the positive reviews and fell for them as well...." Read more

    86 customers mention "Connectivity"6 positive80 negative

    Customers are dissatisfied with the connectivity of the modem. They mention that it has a tendency to drop their internet connection, and that it frequently refuses to connect to the web. It also constantly disconnects all devices from WiFi and that the internet would go off and on.

    "...I baught this not realizing it didnt come with built in wifi connection, i still needed to hook up to a wifi modem, it still was perfect since I had..." Read more

    "...Over time however it has started dropping internet connections. It loses connection and will sit idly for a few minutes before it decides to pickup..." Read more

    "...out of the box set up easy but within 24 hours started constant cycling to find connection...." Read more

    "...Our wifi signal was kind of weak but we were still able to use it." Read more

    19 customers mention "Heating"4 positive15 negative

    Customers are dissatisfied with the heating of the modem. They mention that it runs rather hot at times, gets much warmer than any internet device should, and feels very warm constantly. Some customers also report that the moded has a defective part and was frying itself.

    "...The main reason was heating. These modems gets very warm and needs to run 24/7 there should be cooling units to make them last." Read more

    "...EDIT: Strongly suspect this one is prone to overheating. It’s very small and not particularly well ventilated, and felt very warm constantly...." Read more

    "...However, it does run rather hot at times, and down here in Texas that can be rather detrimental to the operation of the device...." Read more

    "...Haven't checked into this too much, but it seems like this Modem generates less heat than my old one did as well. A great value!" Read more

    Novice Frustration
    3 out of 5 stars
    Novice Frustration
    Apparently I need a WiFi router in order to use WiFi without the ethernet cable and for more than 1 device. For a novice like me I wish this was clearly stated in the description. Very frustrated, especially when working with Xfinity.
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    Top reviews from the United States

    Reviewed in the United States on August 8, 2016
    Size: DOCSIS 3.0Verified Purchase
    Greate ,Cheap , easy to set up , and works perfect !

    Perfect modem if you use Internet on your ps4 or phone and want a stonger connection for multiple devices . Has 3 total wires in the box it comes in. I baught this not realizing it didnt come with built in wifi connection, i still needed to hook up to a wifi modem, it still was perfect since I had a wifi mode already. It was good deal i couldn't pass up ! It connected cox internet service perfectly - Has normal modem issues that you normally expect once in a blue moon , always a common thing when dealing with technology , you can restart the box and the connection will be fixed. 2 months now and still going strong .

    Update: still runs perfectly one year later !!

    Hope this helped anyone !
    Reviewed in the United States on April 28, 2017
    Size: DOCSIS 3.0Verified Purchase
    this modem is really my new favorite. works extremely well, no lag, no internet connection problems like my previous arris which was not good. was really easy to set up and had all the information on how to install to my charter account. after setting this modem up, i was seriously kicking myself in the butt for not purchasing the netgear modem before i bought the arris. i previously had a netgear router and to this day it works perfectly. no routing issues what so ever compared to the arris. i love this modem will from now on only buy netgear.
    2 people found this helpful
    Report
    Reviewed in the United States on December 22, 2015
    Size: DOCSIS 3.0Verified Purchase
    I bought this modem 3 weeks ago, and since then I haven't had no issues whatsoever, I got the same speed as the modem that Time Warner Cable had gave me , no complaints yet. I got 103 Mbps on the download, and almost 10 Mbps upload which I don't care about to much. Works great, set it up its pretty easy , just call your cable company to register the ESN and that's it . If after that you don't have Internet service call Netgear they will help set it up as well.
    One person found this helpful
    Report
    Reviewed in the United States on December 20, 2014
    Size: DOCSIS 3.0Verified Purchase
    Time Warner charges a monthly fee for provided modems but allows customers to purchase their own modem as long as it's on their approved modem list. I purchased this Netgear Modem to lower the cost of my monthly Time Warner internet charges. It will take about 13 months for it to pay for itself. I'm sure it will last much longer than that since I have always had luck with Netgear products. It was very easy to install. I just took the cables off Time Warner's modem and attached them to the new modem. The initial boot-up of the modem took about 5 minutes to complete but the manual said it could take up to 15 minutes. After the initial boot-up I had to call Time Warner to activate it. That process took me about 10 minutes on the phone with a Time Warner tech. The manual lists all the supported cable ISP's along with websites and 800 numbers so you can easily contact your ISP for activation. The manual also includes suggested dialog to use when talking with the tech to make things easier. Comcast customers can activate their modems via Comcast's website. I did a speed test after the activation and everything was as expected.

    Pros:
    Nice Design, Matches the rest of my Netgear equipment.
    Easy to setup.
    Clear instruction manual.
    Lowered my monthly internet bill.
    Can login to the router for configuration, logs, and statuses (Could not with my TW Modem).

    Cons:
    None so far.
    2 people found this helpful
    Report
    Reviewed in the United States on June 16, 2017
    Size: DOCSIS 3.0Verified Purchase
    Right out of the box this product would reboot itself every 1-2 minutes. Obviously your not going to have luck doing anything on the web when you are constantly dropping your connection for a reboot. After doing some research on this issue I quickly discovered that a firmware update should resolve the issue. I verified the current version and compared it to mine and sure enough I was about 6 versions out of date. This is good - it means I have a simple fix ahead of me... or so I thought because updating the firmware should be about the simplest thing you can do on any piece of hardware.

    I expected to find a link in the GUI (this is the interface where you access the controls/settings for the device through an internet browser) which would say something like "Check for updates". But, no such link exists. So, I thought perhaps I could simply download the required files from the support page much like you might for driver.... Nope!

    After doing a little digging on NETGEAR's site I found that in order to update the firmware I had to reach out to the ISP (Internet Service Provider), who in my case is Spectrum (formerly Time Warner Cable). They were very quick to tell me that they can't update the firmware because it's not their device - I purchased it myself, I'm not leasing it from them. So, I reached out to NETGEAR who told me that they can't help me. They reiterated what I previously read on their site that it must be done by the ISP. I tried the Spectrum again hoping the last person that I spoke with there maybe just didn't know what they were doing... and I was told the same thing again. So I called NETGEAR back to find out what can be done. They insisted that they cannot support their own equipment and I needed to get support from the ISP. I started getting seriously frustrated at this point. I asked the rep at NETGEAR "how could you make a product and then not only take away the users ability to maintain their own equipment especially when it comes to firmware updates which are often critical to network security, but you the manufacturer wont support it? How can you rely solely on third-party ISP's all over the globe to maintain your equipment for you?" Instead of responding, he hung up on me. Just like that. I never swore and I never raised my voice. I guess he just didn't have an answer and didn't value me as a customer.

    Long story short - I'll never buy another NETGEAR product again! And I don't recommend you do either!
    44 people found this helpful
    Report
    Reviewed in the United States on October 21, 2015
    Size: DOCSIS 3.0Verified Purchase
    I typically buy products based on reviews and ratings on Amazon. This Modem had quite a high number of reviews and rankings (when I purchased it was at 4.5 stars!) however the reviews have gone down over time. It started out fine, easy to install and ready to go in minutes. Over time however it has started dropping internet connections. It loses connection and will sit idly for a few minutes before it decides to pickup again, or until I manually reset it.

    When it works, it works great. When it drops connection a few times in an hour, it drives me nuts. It usually works ok, but at night it seems to struggle.
    3 people found this helpful
    Report
    Reviewed in the United States on January 17, 2023
    Size: DOCSIS 3.0Verified Purchase
    My Unite lasted me for about 3 years before it started slowing down my internet speed. The main reason was heating. These modems gets very warm and needs to run 24/7 there should be cooling units to make them last.

    Top reviews from other countries

    Zahar Alexandru
    5.0 out of 5 stars Great product, but not for EU use unfortunatelly
    Reviewed in Germany on October 1, 2021
    Size: DOCSIS 3.0Verified Purchase
    The device is missing the EURO-DOCSIS connection. Can be used only in USA.

    The customer support was kind and responsive. They refunded me in no time!
    One person found this helpful
    Report