Troubleshoot your network

Posted on 4 Dec 2007 at 16:41

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If you're still having trouble with your connection, the problem lies elsewhere and you should move to the next step.

I can't see other devices

If you've worked out that your computer is connected to the network but you're still having the same problems, it's likely to be a configuration or software error.

The first thing to do is check that your computer has a valid IP address, as this will confirm that you're on the network. Most people will be using a wireless router, which will automatically hand out IP addresses to computers using the Dynamic Host Configuration Protocol (DHCP). If you're using manual IP address settings, check that you configured your computer correctly.

Sometimes DHCP can go wrong and a computer won't be given an IP address. First, check that your computer is set up for DHCP. In Windows XP, open Network Connections from the Control Panel and double-click the network connection you're using. To get the same view in Windows Vista, open the Network and Sharing Center from the Control Panel and select Manage network connections. Double-click the network connection you're using and click Properties.

For XP and Vista double-click Internet Protocol (TCP/IP) - this is version 4 for Vista - from the 'This conection uses the following items' list. Make sure that both 'Obtain an IP address automatically' and 'Obtain DNS server address automatically' are selected and click OK.

To check in both Windows XP and Vista, start a Command prompt from the Start menu (right-click it and select Run as an administrator if you're using Vista). Type 'ipconfig /all' (without quotes). This will list your computer's network settings. If the IP address listing starts with a 169.x.x.x, your computer hasn't picked up an IP address. Check another computer on the network. If it has a real IP address (which is likely to be something like 192.168.2.1), the problem is with your computer. If the other computer also has a 169.x.x.x address, it's a problem across the network.

In either case this should be easy to fix. Just type 'ipconfig /release' and then 'ipconfig /renew' (without quotes). This will attempt to get a new IP address. If this fails, try to use the Windows Repair option, as described in the previous section. If this doesn't work, your router may have used up the number of IP addresses it can hand out. To fix this you'll need to connect to its web-based management page and reset its DHCP server. To find out how to do this, look in your router's manual.

Once that's done, restart all your computers and devices so that they get new IP addresses. If your computer is still getting a 169.x.x.x address, you should use Windows' System Restore (go to Start, Accessories, System Tools) to go back to a date when your computer was working.

If you've got a proper IP address, you need to check that your computers are on the same network. Compare the settings from two computers. They should both have the same Default Gateway address (this is the IP address of your router, and all network traffic for the internet is sent here). Their IP addresses should start with the same three numbers, followed by different end numbers (192.168.2.2 and 192.168.2.3, for example).

Pinging your devices

Write down the IP address of the computer you want to access. If it's a printer or other network device, you'll need to check the manual to find out how to get its IP address. From your PC, get a command prompt and type 'ping ' where is the address of the device to which you want to connect (ping 192.168.2.3, for example). You should get four replies, showing that you can communicate. If you don't, try pinging your own IP address. If you don't get a reply here, there's something wrong with your computer and you should use Windows Repair option on your network card and perform a System Restore.