Hardware and Internet Setup
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
•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.
Comcast 1-800-COMCAST (1-800-266-2278)
Note: Optimum is a brand name of Cablevision.
Time Warner Cable 1-800-892-2253
Cable Internet Provider Contact Information