This article describes how to troubleshoot problems with
cable modems in Microsoft Windows XP.
Types of Cable Modem Services
There are two types of cable modem services: two-way cable modems
and one-way cable modems. A two-way cable modem receives and sends information
over the cable. A one-way cable modem receives information over the cable and
sends information over the phone line.
Troubleshooting Cable Modem Connectivity
If you are unable to connect to the Internet by using a cable
modem, you should first verify that you are not experiencing a cable outage. If
your television has good cable reception and you are still unable to connect to
the Internet using your cable modem, follow the troubleshooting steps in the
appropriate section below:
Two-Way Cable Service
Two-way cable service uses a network adapter and a cable modem.
You can use standard network connectivity troubleshooting to determine if the
issue is a Windows XP connectivity issue.
additional information about how to troubleshoot network connectivity problems,
click the following article number to view the article in the Microsoft
Troubleshooting problems communicating with a server on the Internet using a dial-up networking connection in Windows 2000, Windows NT 4.0, or Windows NT
One-Way Cable Service
If you are unable to connect to your cable company's Internet
service provider (ISP), the connection is slow, or you connect but are unable
to view any Web pages, use as many of the following steps as needed to resolve
the issue. If one step does not work, proceed to the next step until the issue
- There may be an interrupt request line (IRQ) or
input/output (I/O) address resource conflict between your cable modem and
another hardware device in your computer. This is usually indicated by an
exclamation point in a yellow circle next to the device, or multiple incoming
or outgoing cable modems listed in Device Manager.
For additional information about how to troubleshoot resource
conflicts using Device Manager in Windows XP, click the following article
numbers to view the articles in the Microsoft Knowledge Base:
How to manage devices in Windows XP
How to troubleshoot unknown devices listed in Device Manager
Explanation of error codes generated by Device Manager
If multiple incoming or outgoing cable modems are
listed in Device Manager, remove the duplicate modem entries, and then follow
the steps in the article to troubleshoot the resource conflict. To remove
duplicate cable modem entries in Device Manager, follow these steps:
Troubleshooting device conflicts with Device Manager
- Click Start, click Control Panel, and then double-click System.
- Click the Hardware tab, and then click Device Manager
- Double-click the Modem Branch to expand it.
- Click a duplicate cable modem, and then click Remove.
- After you remove all duplicate cable modems, click Close, and then restart your computer.
- If your cable modem is redetected every time you start your
computer, the modem's software may be unable to communicate with the modem
during the boot process. To resolve this issue, uninstall the modem driver and
then install the latest driver for your cable modem. For information about how
to obtain and install the latest driver for your cable modem, contact your
cable company's ISP support group or your modem's manufacturer.
- If you are unable to connect to the Internet at all,
contact your cable company's ISP support group to verify that the proxy server
address, Domain Name Service (DNS) address, line-in frequency, and line-out
phone number are correct.
If you are having performance problems
while connected to the Internet, contact your cable company's ISP support group
to verify that the connection parameters are in an acceptable range. Some cable
modems include a utility that automatically obtains the correct cable
connection parameters. If your modem does not include a utility such as this,
you can usually obtain connection parameters from your cable company's ISP
- If you have more than one network adapter on your
multihomed Windows XP-based computer that is using Transport Control
Protocol/Internet Protocol (TCP/IP) address from the Automatic Private IP
Addressing (APIPA) subnet range 169.254.0.0-169.254.255.255, subnet mask
255.255.0.0, routing to this subnet may not work.
For additional information about this issue, click
the following article number to view the article in the Microsoft Knowledge
Routing does not work when multiple adapters use automatic private IP addressing simultaneously
: Some cable modems can be reset by unplugging and powering down
the modem for 10 seconds and then powering the modem back up again.