Troubleshooting Your Home Network

Troubleshooting your network can take on many forms. But most problems tend to repeat themselves. The first step is usually distinguishing between a software problem and a hardware problem. Unless you have specific reasons to question some other aspect, start troubleshooting by checking the hardware on your network. One of those reasons might be that you've just installed some new software that affected network settings.

How you do that in detail depends on how your network is arranged. Assume, for simplicity, that you have three computers connected to a simple hub or switch. Suppose one computer is connected to the Internet, and uses Internet Connection Sharing. It will form the focus of the network. Check its IP address, which might look like 192.168.0.1. This may be the address of the router instead. See the instructions of your router for details.

To check an IP address, you can use Control Panel/Network Connections (Windows XP). But it's a good idea to get used to executing command line utilities to diagnose network issues. Click Start/Run, then type 'cmd' into the dialog box, leaving off the quote marks. This opens a 'DOS window'. Type: ipconfig/all. You'll see the IP address and related information.

Next, ping the IP address of the second or third computer on your network. If you get back 'Request timed out' you have a loss of connectivity between the computer executing the ping and the one you are pinging.

Ping from 192.168.0.1 to 192.168.0.2, then from the second to the reverse. By using different computers to ping to and from you can often isolate where the problem is.

Check the lights on the network adapter (NIC or network interface card) on both computers. They should be green and blinking when doing the ping. Check the hub or switch to which they are attached. The light should be lit continuously. Similar considerations apply if you are using a router.

If one of the lights is not lit, check the cables attached to that port. It's rare, but not too rare, for a cable or connector to go bad. What's less rare is for a newly attached device's cable or connector to malfunction. Cables get bent, crimped and subject to a number of physical stresses that can cause the wires inside to come loose. It only takes one to cause the whole cable to be bad.

Similarly, if you have a wireless network, check the lights on the adapter(s) and the router. Most routers will come with diagnostic software that will help you trace down the source of the problem.

For cabled or wired networks, a cable diagnosis meter is a handy device. If you can afford one, something called a sniffer is very handy for either type of network. With it, you can see packets being passed back and forth and gather other useful information.