NETGEAR CM400 High Speed Cable Modem Instruction Manual

1. Overview

The NETGEAR CM400 High Speed Cable Modem provides a reliable connection to high-speed cable Internet, supporting speeds up to 340 Mbps. It is CableLabs certified and features DOCSIS 3.0 technology, offering speeds significantly faster than DOCSIS 2.0. This modem is compatible with major U.S. cable Internet providers such as Xfinity by Comcast, Cox, and Spectrum.

Key features include:

• Broad Compatibility: Certified by Xfinity by Comcast, Cox, and Spectrum. Note: Not compatible with Verizon, AT&T, CenturyLink, DSL providers, DirecTV, DISH, or any bundled voice service.
• Cost Savings: Replaces rented cable modems, potentially saving on monthly rental fees.
• Optimized Speed: Best suited for cable provider plans with speeds up to 100 Mbps, while supporting up to 340 Mbps.
• Router Compatibility: Works with any Wi-Fi router by connecting to the modem's Ethernet port.
• Connectivity: Equipped with 1 Gigabit Ethernet port for connecting to a computer or a separate Wi-Fi router.
• Advanced Technology: Engineered with 8x4 channel bonding and DOCSIS 3.0 for enhanced performance.

2. Setup

Setting up your NETGEAR CM400 Cable Modem is a straightforward process. Follow these steps for a quick installation:

1. Disconnect Old Modem: Unplug and remove your existing cable modem.
2. Connect Coaxial Cable: Connect the coaxial cable from your cable wall outlet directly to the cable port on the NETGEAR CM400 modem. Ensure the connection is tight.
3. Connect Power: Plug the power adapter into the modem's power port and then into an electrical outlet. The modem will begin to power on.
4. Connect to Router/Computer:
   • For a Wi-Fi Router: Connect an Ethernet cable from the modem's Gigabit Ethernet port to the Internet (WAN) port on your Wi-Fi router. Power on your router.
   • For a Computer: Connect an Ethernet cable directly from the modem's Gigabit Ethernet port to the Ethernet port on your computer.
5. Wait for Indicators: Allow the modem approximately 10 minutes to connect to the cable network. The Online LED indicator should turn solid green, indicating a successful connection.
6. Activate Internet Service: Open a web browser on a connected device. You may be redirected to your Internet Service Provider's (ISP) activation page. Follow the on-screen prompts. If not redirected, refer to your ISP's instructions or contact their customer support. You will typically need your modem's MAC address, which is located on a label on the modem.

3. Operating the Modem

Once successfully set up and activated, your NETGEAR CM400 modem will provide Internet access to your connected devices. The modem operates by converting the coaxial cable signal into an Ethernet signal, which can then be distributed by a Wi-Fi router or directly to a computer.

LED Indicators

The front panel of the modem features several LED indicators that provide status information:

• Power: Indicates if the modem is powered on.
• Downstream (Down Arrow): Indicates the downstream connection status.
• Upstream (Up Arrow): Indicates the upstream connection status.
• Online (Globe Icon): Indicates successful connection to the Internet. A solid green light means the modem is online.
• Ethernet (Two Rectangles): Indicates Ethernet activity.

For optimal performance, ensure all relevant LEDs are solid green after setup.

4. Maintenance

To ensure the longevity and consistent performance of your NETGEAR CM400 Cable Modem, consider the following maintenance tips:

• Regular Restart: If you experience slow speeds or connectivity issues, try power cycling the modem. Unplug the power adapter, wait for about 30 seconds, and then plug it back in. Allow the modem a few minutes to re-establish its connection.
• Proper Ventilation: Ensure the modem is placed in a well-ventilated area to prevent overheating. Avoid placing it in enclosed spaces or covering its ventilation holes.
• Secure Connections: Periodically check that all cable connections (coaxial and Ethernet) are secure and tight. Loose connections can lead to intermittent service.
• Cleanliness: Keep the modem free from dust and debris. Use a soft, dry cloth to gently clean the exterior.

5. Troubleshooting

If you encounter issues with your NETGEAR CM400 Cable Modem, refer to the following troubleshooting steps:

• No Internet Connection / Online LED Not Solid:
  • Verify all cables are securely connected.
  • Perform a power cycle (unplug, wait 30 seconds, plug back in).
  • Contact your Internet Service Provider (ISP) to ensure your service is active and that the modem is properly provisioned on their network. You may need to provide the modem's MAC address.
• Slow Internet Speeds:
  • Confirm your internet plan speed with your ISP. The CM400 is best for plans up to 100 Mbps.
  • Perform a power cycle of both the modem and your router.
  • If speeds remain low, contact your ISP. Issues such as a locked boot file or network configuration problems may require their intervention.
• Modem Not Recognized by ISP:
  • Ensure your ISP supports the NETGEAR CM400 model.
  • Contact your ISP's activation line. Be prepared to provide the modem's MAC address and serial number.

6. Specifications

7. Warranty and Support

The NETGEAR CM400 Cable Modem typically includes a manufacturer's warranty. For specific warranty details and duration, please refer to the documentation included with your product or visit the official NETGEAR support website.

NETGEAR offers 24/7 technical support. Additionally, a 90-day complimentary technical support period is often included with the purchase. For assistance, visit netgear.com/support.

Important Note: This product is sold as is. It is the user's responsibility to ensure compatibility with their Internet Service Provider (ISP) before purchase. The manufacturer is not responsible for ensuring the modem functions with all ISPs.