Troubleshooting Broadband Cable Modem Problems

If you've been accessing the Internet through a broadband cable modem but now you can't connect, this guide provides some troubleshooting tips.

Check Your Modem's Front Panel LEDs

The LED's on the front of your modem provide information about it's functioning. The Power and Cable LEDs should be on. The PC LED should be blinking. This "PC Activity" light indicates that the PC and the Modem are "shaking hands" indicating they are ready to talk to each other. If it's off or on solid, there is a bad connection or software configuration problem.

The Send LED should be blinking when your PC is sending data packets to the Internet. The Receive LED should be blinking when your PC is receiving data packets to the Internet. If they're off, it means your PC is not sending or receiving data. If they're on solid, it means you have a software or hardware problem.

Check All Connections

Make sure the power cord is securely plugged into the modem and into the wall outlet. Check that the coaxial cable is connected securely to the back of the modem and to the wall faceplate (don't over-tighten). Check that the Ethernet cable is securely connected to the modem and to the computer.

Power Cycle Your Modem and Router

If you are using a router, remove power from the router and the modem. Wait ten seconds and then power the modem back on, then power the router back on. Give them both time to reboot. Then try connecting to the Internet again with your computer.

Reboot your Computer

Shut down your computer, wait ten seconds and then restart. After your computer reboots try connecting to the Internet.

Remove your Router from the Configuration

If you still cannot connect the Internet, eliminate the router from the setup. Connect your computer's Ethernet port directly to the modem's Ethernet port with one of the network cables. Once you've done this, you'll have to power cycle the modem and reboot the computer. After the modem and computer reboot try connecting to the Internet again.

Examine Your IP Address

In the Start button Search text box type cmd.exe and press the [Enter] key. This will open a DOS command prompt. At the command prompt type ipconfig. This should return information about your TCP/IP connection. Examine this information to make sure your Ethernet adapter has a local IP address, subnet mask, and default gateway address. To close the command prompt type exit and press the [Enter] key.

To renew your PC's IP address, open a command prompt, and type in ipconfig with the release option (ipconfig /release [Enter]), then with the renew option (ipconfig /renew [Enter]). Close the command prompt by typing exit and pressing the [Enter] key. Try connecting to the Internet again.

Examine Installed Protocols

1. In Control Panel select the Network and Internet group.
2. In the Network and Internet group select the Network and Sharing Center.
3. On the Network and Sharing Center page, under View your active networks, click on Local Area Connection.
4. In the Local Area Connection Status dialog box, click on the [Properties] button.
5. If the User Account Control warning box appears, click on the [Yes] button.

In the Local Area Connection Properties dialog box that appears, make sure the following protocols are checked:

[x] Client for Microsoft Networks
[x] QoS Packet Scheduler
[x] Internet Protocol Version 6
[x] Internet Protocol Version 4
[x] Link-Layer Topology Discovery Mapper I/O Driver
[x] Link-Layer Topology Discovery Responder

Double-click on Internet Protocol Version 6, and in the Internet Protocol Version 6 Properties dialog box that appears, make sure the "Obtain IP Address automatically" radio button is checked, and the "Obtain DNS Server Address automatically" radio button is checked. Do the same thing for Internet Protocol Version 4.

Install any networking components necessary, make any configuration changes necessary. Reboot the PC to put the changes into effect. Then try connecting to the Internet again.

Seek Technical Support

If you still can't connect to the Internet, at this point all your easy troubleshooting options have been exhausted. It's time to call your IP's technical support via telephone. Don't call them now if you don't have the time or patience to deal with it. When you're ready to work with technical support, make sure to have a telephone nearby your computer as the technician may ask you to assist with troubleshooting.