Disable the Laptop’s Wireless Adapter
If you cannot connect your laptop using an Ethernet cable, make sure the laptop’s wireless adapter is disabled. To disable it in Windows XP, click the Start button and open the Control Panel. Double-click Network Connections. Right-click Wireless Network Connection and select Disable from the drop-down list.
If you are using a laptop with Windows Vista, click the Start Button and type Network and Sharing into the Start Search box. Select Network and Sharing Center from the Programs list. Select Manage Network Connections from the left pane of the window. The Network Connections window will open. Click on Wireless Network Connection. Select Disable this Network Device at the top of the window.
Troubleshoot the Network
After disabling the laptop’s wireless connection, be sure to restart the computer before trying to connect with the Ethernet cable again. If you still cannot connect the laptop to the network with an Ethernet cable after rebooting, check to make sure there is not a problem with the network itself. If there are others nearby connected to the same network, such as in your office, dorm or another public location, ask them whether they are currently able to connect to the network. If no one else is using the network, contact the system administrator or your Internet service provider to see if there may be an outage. This step can save you plenty of time troubleshooting if there is an outage in your area!
Troubleshoot the Ethernet Cable
If there is no problem with the network itself, the reason that you cannot connect the laptop may be the Ethernet cable. Make sure that the Ethernet Cable is securely connected to both the laptop and the wall outlet. If possible, try connecting the Ethernet cable into another wall jack or port on the router, and then try using a different Ethernet cable. The Ethernet cable you are using may be damaged.
Photo credit: Christian Kitazume
Troubleshoot Network Settings
If the Ethernet cable does not seem to be the reason why you cannot connect to the network, check the laptop’s network settings. In Windows XP, open the Control Panel and select Network Connections. Open Local Area Connection and check the status of the connection.
In Windows Vista, go to the Network and Sharing Center and select Diagnose and Repair from the left pane and wait for the results.
If the Local Area Connection is listed as Disabled, right-click it and choose Enable.
If it says that the network adapter is unplugged and you have ruled out a problem with the Ethernet cable and port, the laptop’s network adapter may have failed. Try using the same Ethernet cable on another computer. If you are able to connect to the network on another computer using the same Ethernet cord, contact the laptop’s manufacturer, a computer repair technician or replace the network adapter yourself.
If it says Limited or No Connectivity, there may be a problem with the laptop’s modem or router. It might also mean there is a problem with the laptop’s TCP/IP settings. For detailed steps on troubleshooting your laptop’s TCP/IP address, check out the Bright Hub tutorial Troubleshooting TCP/IP & IP Addresses on Networks.