NETGEAR DOCSIS 3.0 340Mbps Cable Modem for Comcast, Time Warner, Spectrum Cable, Cox, Charter, Cablevision, Brighthouse  (CM400-1AZNAS)

NETGEAR DOCSIS 3.0 340Mbps Cable Modem for Comcast, Time Warner, Spectrum Cable, Cox, Charter, Cablevision, Brighthouse (CM400-1AZNAS)

List Price: $44.99
Price: $39.99 Details

Availability: Usually ships in 24 hours
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30 new or used available from $32.74

Average customer review:
(4.0 stars, based on 4219 reviews)

Product Details

  • Size: Up to 340 Mbps - (8x4)
  • Color: Black
  • Brand: NETGEAR
  • Model: CM400-1AZNAS
  • Published on: 2015-07-07
  • Released on: 2015-08-17
  • Dimensions: 2.05" h x 7.17" w x 9.46" l, 1.17 pounds


  • Compatible with Comcast, Time Warner, Century Link, Spectrum Cable, Cox, Charter, Cablevision, Brighthouse Call provider if not listed here. Requires Cable Internet Service and approved for plans up to 340 Mbps
  • Not compatible with Verizon FiOS, AT&T U-Verse, or bundled voice services
  • Cable Modem only (no WiFi router)
  • Eliminate your cable modem monthly rental fee
  • If the unit does not work , Check the connection of your devices. Ensure that each connection is securely and tightly plugged in. Try to refresh your cable connection by power cycling your network, If power cycling did not work, download the latest firmware of your router. After you have the downloaded the firmware, please upgrade your routers firmware manually, If the above steps did not resolve your issue, you may need to reset your router.

The NETGEAR CM400 High Speed Cable Modem provides a connection to high-speed cable Internet, up to 340 Mbps. 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

Most helpful customer reviews

327 of 347 people found the following review helpful.
4Great modem but gets extremely HOT
By Richard N
This modem was a black Friday purchase. Before I start my quick list of credentials are: I work from home (so it gets a lot of use) and in IT security. With that said I was getting tired of Comcast throttling my speeds during certain hours of the day and night, so I purchased this modem to attempt to by pass them all together. I pay for 105 down and definitely wasn't getting that. Now my modem and router are on the 3rd floor and I work on the second floor. I know the router is one main cause of speed issues however 24 down is unacceptable in my eyes and when I ran the speed test next to the router it was only around 40ish.

So enter my new Netgear modem. My new speed tests on the 3rd floor (next to the router is about 70 to 80 down and about 15 up. On the second floor where I work (just ran a speed test as I am writing this review / See pictures attached) I am getting 63.68 down and 10.26 up; which is a HUGE improvement from using the Comcast modem.

Again my router is getting old and am looking to buy a new one soon, however the huge difference in speeds between this Netgear modem and the Comcast one are painstakingly clear. Oh and for you gamers that use a direct connection (I direct connect my Xbox one into LAN port 1) when I ran a speed test though the Xbox it showed 122 down (which is higher than I am paying for).

I have to say that I do love it but there is a few concerns. Review notes below:

-Very noticeable speed increase from Comcast Modem
-Install went quickly. Called Comcast, gave them (if I remember correctly) the MAC and serial number on the modem and I was up and running within minutes.

-My one and only major concern is how HOT it gets. I am not sure if this is normal for this modem and I still need to contact netgear about this. When I say hot; I don't mean warm to the touch, I mean borderline that I am worried the components are melting / fusing together on the inside. This is why I only give it 4 stars and not 5

Hope this review helped and I will try to answer any questions you all have.

175 of 191 people found the following review helpful.
5No more cable modem rental fees for me!!
By Christopher Malone
It was time to start trimming my Time Warner Cable bill. So, I purchased this puppy. Yeah, it has a cheap price tag, but this little baby packs a punch. I pay for the Extreme package via Time Warner. I was averaging 80 megs down. After installing this and getting it activated, my download speeds are averaging over 115 megs down - that's both wirelessly and hard-wired. The setup is simple. 1. Remove your current cable modem. 2. Put this one in it's place. 3. Hard-wire it to a laptop or a desktop (yellow cable to the yellow port on back of cable modem, the other end to the internet port on your laptop or desktop. 4. Power on the modem (making sure you have already connected the coaxial cable as well. (When the globe stays a solid green with no blinking, it is recognized as being connected. 5. Turn to the activation page in the mini manual that comes with it. It will show various internet providers and their perspective links. 6. Open up a browser (with pop-up blocker offf) and follow the prompts. Odds are in favor you will get "due to your account settings, this will not work - call the 1-800 number shown." That's okay, call it. Tell the operator you are installing your own cable modem. The operator will ask for the MAC address (found both on the box and bottom of cable modem). Agent on the phone will first remove your current cable modem from your plan (or else, this will never work). You will power it off upon request, and back on again 30 seconds later. Go to a website of choice - and wa-la, you are back online!! No more cable modem rental fees!! BTW, I work in the IT field, and have for 25 years. This will be all the modem you ever need unless you plan to go over 450 megs in the future. I have the following items that may be online at any time and all at once: Xbox One, PS3, Two laptops, One desktop, one cell phone, and one tablet. I can play Netflix on all devices (4 at once since that's my Netflix account package), and there is no buffering at all. I bundled this with the Netgear WNDR4500 Dual Ban Gigabit Wifi Router. Here's my layout. Cable Modem feeds the router. The router feeds my 16-port switch. I work on computers on the side, so the switch comes in handy. Any questions? Feel free to ask me. Trim your cable bill and get this or any cable modem for that matter. Note, this is a cable modem only that does not supply wifi. It only has the internet-out port. There are no other ethernet ports on it. So, upgrade your router or get one. The model I mentioned above is a great match. You are welcome!!

35 of 37 people found the following review helpful.
5If your cable Internet provider supports it, then this is an excellent choice for a modem.
By Nick Mnemonic
I picked up this modem as I had a 2-in-1 (modem & router) that got aged and started flaking out on me. And unfortunately, the model I had could only be managed by the cable company (updates and what have you). I decided to get new equipment and go back to the good old days where my modem and router were completely separate for multiple reasons, 1) if one goes I can replace it without having to replace the whole setup, and 2) if nothing else I can go back to being able to manage my router on my own.

I picked this up along with the Netgear Nighthawk AC1900 router. The combination of the pair are phenomenal. I now actually get the speeds I pay for, and my internal network is blazing.

With it's multiple downstream and upstream channels, we can have everyone on their individual devices doing things like gaming and streaming without even the slightest blip in content continuity.

The only thing I'd say to be aware of is that if you're buying your own router, double-check that it's supported by your cable Internet provider first.

All in all, this router does everything I wanted it to.

See all 4219 customer reviews...