NETGEAR CM400 User manual

350 East Plumeria Drive
San Jose, CA 95134
USA
August 2014
202-11412-01
CM400 High Speed Cable Modem
User Manual

2
CM400 High Speed Cable Modem
Support
Thank you for selecting NETGEAR products.
After installing your device, locate the serial number on the label of your product and use it to register your product at
https://my.netgear.com. You must register your product before you can use NETGEAR telephone support. NETGEAR
recommends registering your product through the NETGEAR website. For product updates and web support, visit
http://support.netgear.com.
Phone (US & Canada only): 1-888-NETGEAR.
Phone (Other Countries): Check the list of phone numbers at http://support.netgear.com/general/contact/default.aspx.
Compliance
For regulatory compliance information, visit http://www.netgear.com/about/regulatory.
See the regulatory compliance document before connecting the power supply.
Trademarks
NETGEAR, the NETGEAR logo, and Connect with Innovation are trademarks and/or registered trademarks of NETGEAR, Inc.
and/or its subsidiaries in the United States and/or other countries. Information is subject to change without notice.
© NETGEAR, Inc. All rights reserved.

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Contents
Chapter 1 Hardware and Internet Setup
Unpack Your Cable Modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Back Panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Product Label . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Attach the Feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Cable Your Cable Modem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Contact Your Cable Internet Provider and Set Up Internet Service. . . . . . . . . . . 9
Chapter 2 Manage and Monitor
Log In to the Cable Modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Specify the Cable Connection Starting Frequency . . . . . . . . . . . . . . . . . . . . . . . 12
View Cable Modem Initialization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
View Cable Modem Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
View and CLear Event Logs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Change the admin Password . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Reboot the Cable Modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Reset the Cable Modem to Factory Default Settings . . . . . . . . . . . . . . . . . . . . . 18
Use the Reset Button on the Back Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Use the Factory Reset Software Button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Chapter 3 Troubleshooting
Use LEDs to Troubleshoot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Cannot Log In to the Cable Modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Troubleshoot the Cable Internet Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Appendix A Technical Specifications

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1
1. Hardware and Internet Setup
The NETGEAR CM400 High Speed Cable Modem provides a connection to high-speed cable
Internet with speeds up to 340 Mbps.1The cable modem is certified by all major cable Internet
providers. A Gigabit Ethernet port provides fast access and downloads. The cable modem
supports IPv4 and IPv6 address assignment by cable Internet providers.
This chapter covers the following topics:
•Unpack Your Cable Modem
•Front Panel
•Back Panel
•Product Label
•Attach the Feet
•Cable Your Cable Modem
•Contact Your Cable Internet Provider and Set Up Internet Service
Note: For more information about the topics covered in this manual, visit the
support website at http://support.netgear.com.
1. Maximum rate is derived from DOCSIS 3.0 specifications and actual throughput varies depending on your Internet subscription with your provider.

Hardware and Internet Setup
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CM400 High Speed Cable Modem
Unpack Your Cable Modem
Your package contains the following items.
Ethernet cable Power adapter
Cable modem Attachable feet
Figure 1. Package contents
Front Panel
The cable modem provides status LEDs on the front.
Power LED Downstream LED
Upstream LED
Internet LED
Ethernet LED
Figure 2. Cable modem front view

Hardware and Internet Setup
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CM400 High Speed Cable Modem
You can use the LEDs to verify status and connections. The following table lists and
describes each LED on the front panel of the cable modem.
Table 1. LED descriptions
LED Description
Power • Green. Power is supplied to the cable modem.
• Off. No power is supplied to the cable modem.
Downstream • Solid green. One or more downstream channels are locked.
• Blinking green. The cable modem is scanning for a downstream channel.
• Off. No downstream channel is locked.
Upstream • Solid green. One or more upstream channels are locked.
• Blinking green. The cable modem is scanning for an upstream channel.
• Off. No upstream channel is locked.
Internet • Solid green. The cable modem is online.
• Blinking green. The cable modem is synchronizing with the cable provider’s cable
modem termination system (CMTS).
• Off. The cable modem is offline.
Ethernet • Green. A device is connected to the Ethernet port and powered on.
• Off. No device is connected to the Ethernet port.
Back Panel
The back panel provides the connections and button shown the following figure.
Power adapter input
LAN Gigabit Ethernet port
Coaxial cable connector
Reset button
Figure 3. Cable modem back panel
Note: The Internet LED is also referred to as the Online LED.

Hardware and Internet Setup
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CM400 High Speed Cable Modem
Product Label
The product label on the bottom of the cable modem displays the serial number and MAC
address of the cable modem and login information, including the default IP address,
default user name, and default password.
Figure 4. Product label
Attach the Feet
The cable modem functions well in either a horizontal or vertical position.
If you prefer to place the cable modem in the upright (vertical) position, attach the feet that
come with the cable modem.
To attach the feet:
1. Hold the cable modem in the upright position with the left side of the cable modem pointing
down.
2. Snap the feet onto the cable modem.
Figure 5. Attaching the feet

Hardware and Internet Setup
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CM400 High Speed Cable Modem
Cable Your Cable Modem
The cable modem provides a connection between your cable Internet provider’s network and
your computer, router, or WiFi router.
Computer,
router, or
WiFi router
Cable modem
Coaxial cable to cable outlet
Ethernet
cable
Figure 6. Cabling the cable modem
To cable your cable modem:
1. Connect a coaxial cable.
Use the coaxial cable that your cable company provides to connect the cable port on the
cable modem to a cable wall outlet or a line splitter.
Note: If Charter is your cable Internet provider, Charter recommends
connectingyour cable modem directlyto a cable wall outlet.Ifyou must
use a splitter, use a splitter that is rated at 3.5 dBmv.
Note: If Comcast Xfinity is your cable Internet provider, Comcast Xfinity
recommends connecting your cable modem directly to a cable wall
outlet.
2. Connect the power adapter provided in the package to the cable modem and plug the power
adapter into an electrical outlet.
The Power LED lights green.
3. Turn off the computer, router, or WiFi router to which you intend to connect the cable
modem.
4. Use the Ethernet cable provided in the package to connect the Gigabit Ethernet port on the
cable modem to an Ethernet port on a computer, router, or WiFi router.

Hardware and Internet Setup
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CM400 High Speed Cable Modem
5. Turn on the computer, router, or WiFi router.
6. Wait for the cable modem to come online.
It takes at least 15 minutes for the cable modem to come online on the network. During
this time, the Downstream LED and Upstream LED might blink.
After the cable modem registers with your cable Internet service provider, the
Internet LED lights green. Even though an Internet connection is established,
Internet service is available only after you set it up with your cable Internet provider.
For information about how to set up your Internet service, see Contact Your Cable
Internet Provider and Set Up Internet Service on page 9.
Contact Your Cable Internet Provider and Set Up Internet
Service
You must contact your Internet provider and tell them that you are using a new cable modem.
Note: If Comcast Xfinity is your cable Internet provider, you do not need to
call. Just launch a web browser. You are redirected to the Xfinity
self-activation page on which you can enter your Xfinity credentials.
To set up your Internet connection:
1. Contact your cable Internet provider and inform them that you are installing a new cable
modem that you bought from a retail store.
Provide your cable Internet provider with the cable modem’s model number, which is
CM400.
Note: The cable modem is certified by all major cable Internet providers.
You can also visit your cable Internet provider’s website and follow the onscreen
instructions to set up your Internet service.
Cable Internet Provider Contact Information
Bright House Networks 1-866-898-9101
support.brighthouse.com
Cablevision cablevision.com
optimum.com/contactus.jsp
Note: When you attempt to contact Cablevision online, you are directed to the
Optimum web page. Optimum is a brand name of Cablevision.

Hardware and Internet Setup
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CM400 High Speed Cable Modem
Note: The contact information listed might change. You can also find the
contact number in your monthly Internet service billing statement.
2. When asked, provide the cable modem’s serial number and MAC address, which are on the
product label (see Product Label on page 7).
3. Wait for your cable Internet provider to confirm that your cable modem is active.
4. If you do not get an Internet connection with the cable modem, ask your cable Internet
provider to look for your cable modem online, and do one of the following depending on
what your cable Internet provider tells you about your cable modem:
•If the cable modem is not visible, your cable Internet provider can give you instructions
to verify why the cable modem does not connect with your high-speed Internet
service.
•If the cable modem is visible to your cable Internet provider, reboot the computer,
laptop, router, or WiFi router that is connected to the cable modem. Try checking your
online status again.
Charter 1-888-438-2427
install.charter.com
Comcast 1-800-COMCAST (1-800-266-2278)
comcast.com/activate/
Cox 1-877-891-2899
cox.com/residential/home.cox
Optimum play.optimum.net
optimum.net/support/phone-list
Note: Optimum is a brand name of Cablevision.
Time Warner Cable 1-800-892-2253
timewarnercable.com
Cable Internet Provider Contact Information