Windows Network Troubleshooting: Tips and Techniques

This article provides ways to analyze and troubleshoot network problems in Windows using the built-in tools. The troubleshooting steps mentioned in this article could still be used in different versions of the Windows operating system, such as Windows 2000, Windows XP and the coming stable version of Windows 7. Windows 7 could offer a lot of built-in network diagnostics tools as expected, but since it is still in beta as of September 2009, lot of things can change.

However, to maximize the learning process, it is necessary to employ general or universal techniques for network troubleshooting, so that what you learn here will be applicable to any Windows operating system version. The following are common Windows network problems and the recommended troubleshooting tips.

Local Area and Wide Area Network Problems

In any type of Windows-based network, the simplest is a local area network. This is a network of computers in close proximity under the same routers. For example, a home or small office network is a local area network interconnected via a router. There are often a lot of problems in dealing with a LAN. Some of the most common will be discussed on the following pages.

Unplugged Network Cable

You receive the message “A Network Cable is Unplugged.” This error is self-explanatory, though confirmation can point out the root cause of this problem.

Use this method to troubleshoot if you know the router IP address: go to Start -> Run and type CMD. The DOS screen will pop up. In the DOS command prompt, type:

ping 192.168.1.1

Then press enter. This assumes your router IP address is 192.168.1.1. If you see a “Destination host unreachable” or timeout ping reply such as the screen shot below under “Ping Reply of Network cable Unplugged,” it confirms that the connection from your computer to the router has been disconnected physically. Or if you are using wireless, this could mean a problem with wireless components, such as having the antenna off.

The router IP address can change; it can be 192.168.1.1 or 192.168.2.1, or even become a completely different figure from the one shown above. If you do not know the router's IP address, you'll need to use a different method.

If you don't know the router's IP address, the easiest way to start troubleshooting is to type this into the DOS prompt and press enter (Start -> Run -> CMD):

ipconfig

In the results, look for a “Media Disconnected” message. If you find it, it confirms that there is no connection between the router and your computer (this also applies to wireless connections). See the details of this diagnostic test below:

To solve this problem, you need to trace the connection between the router and your computer. Look for a disconnected LAN cable; even a loose connection can cause this problem.

If you are using a wireless router, make sure you have configured your computer to communicate properly with wireless devices; things like having your wireless antenna off can also cause this problem. Detailed troubleshooting for these devices is beyond the scope of this article; in this case, please refer to your wireless router's or wireless LAN card's manual.

Limited Connectivity

The message signaling this issue is “Local Area Connection: This Connection has limited or no connectivity.”

This is a trickier type of LAN connection problem, with many possible root causes. To troubleshoot, follow the diagnostic flow chart below.

For wired and wireless LAN connections:

You need to first check the network cable to see if it is disconnected (for wireless, check to see if the antenna is on or the wireless configuration is okay). Sometimes this is the cause, and you can refer to the troubleshooting procedure discussed above. If you are sure that the network connection is okay, there could be problem with your router configuration. The following is the “wrong router configuration troubleshooting” procedure:

Step 1: Double check to make sure this is a real error. Sometimes this error can appear despite there being no problem at all. A simple way to check is to open your browser to see if you can connect to the Internet. If you cannot connect, then proceed to step 2.

Step 2: Go to Start -> Run -> CMD, and then at the DOS command prompt, type and enter:

tracert yahoo.com

This command will trace the connections starting from your computer all the way to the computer where yahoo.com has been hosted, to find out where the connection has been broken.

The purpose of doing this test is to find out whether or not your router is working. If it is working, it should not give a “timeout” result, but instead be able to pass a packet starting from your computer, to the router, and then to your ISP's computers, and finally to the hosting computers of the website.

Below is an example of a “working” router:

Based on the above results, the router with IP: 192.168.1.1 passed the packet at ~2ms, and then it was received by the ISP's IP around 22ms later. This means that the broken connection is not caused by the router.

Router Problem

If it turns out, however, that the router was NOT able to pass a packet to the ISP (or you received no ping reply in ms at the router), the router has a problem. If you configured your LAN like this (one of the most common configuration in home and office):

http://www.microsoft.com/resources/documentation/
windows/xp/all/proddocs/en-us/hn_topology24_art.mspx?mfr=true

and you use a router (wire or wireless type) as a “residential gateway,” try resetting your router. This involves clicking the reset button (a “long press”). Discussion of the router reset button is out of the scope of this article; it is suggested that you refer to the router’s manual. Once the router has been reset, go to: Control Panel -> Network Connections, right click on the “Local Area Connection” and click “repair.” Wait until the connection repair is complete. After that, try pinging your router at 192.168.1.1.

Sometimes you might not know the router's IP address. In this case, try to run the command in the DOS prompt:

ipconfig

Look for the IP address assigned to “Default Gateway.” An example is shown in the screen shot below:

In the above screen shot, the router IP address is 192.168.2.1. If you receive a ping reply, configure your router again to work on a Windows network (by going to router control panel: http://192.168.2.1 at the browser). Detailed settings are discussed in yesterday's article, Windows XP Home Network Setup: Essential Steps.

What if the router is okay and you are still receiving the “Limited or no connectivity” error? If you see the response of the tracert command from the DOS diagnostic test above, you should be receiving a “failed” or “timeout” reply on the ISP side. So this means that the ISP (Internet service provider) is currently having technical issues with providing Internet connections to their customers.

In this case, the best solution is to call them and ask about the status of their repairs.