Troubleshooting Network Connection Problems

By | April 30, 2009

Network and internet connectivity issues can be caused by a whole host of different things ranging from hardware failures including cabling and NIC card to ISP outages and router failures. Previously, I mentioned how to set up a remote access VPN connection; now let’s take a look at how to troubleshoot network connection problems.

The most important thing to remember when troubleshooting anything is to check the easiest and most obvious possibilities first. It can certainly be embarrassing when it takes several days to determine the problem was a simple cabling issue after you have replaced the NIC card several times, and maybe yelled at your ISP.

So first thing is to check to see if all the computers are having the same problem, or is it only one machine. If all machines on the network are having trouble you should begin looking at the network hardware (routers ISP cabling etc)

A common cabling issue that can cause a large amount of confusion is when you have accidentally plugged in a crossover network cable instead of a straight through network cable. The difference between the two cables is very subtle but will cause a total failure in connectivity. A straight through cable can be identified by the order of the colored cables inside the plastic fitting at each end of the cable. The colors on both ends of the cable should be in the same order.

This is an example of what both ends of a straight through cable should look like. This is the type of cable you SHOULD be using in your home network when you are using a router.

Straight through cable pin assignment

Straight through cable pin assignment

This is an example of what both ends of a crossover cable should look like. This is the type of cable you SHOULD NOT be using to connect a computer to your router.

Crossover cable pin assignment

Crossover cable pin assignment

Assuming only one machine is having difficulty you should continue looking at:

  • Changing the network cable between the problem machine and the network device (router). When changing the cabling as a test you might consider taking the cable from one of the other network machines that you know IS working; this way you know you are testing with a functional cable.

If changing the cable still does not fix the problem you might want to look in the network connection properties. Go to Start>Control Panel>Network Connections.


In the example above, the computer is currently connected to the internet successfully using a wireless connection. The wired connection is not functioning possibly because the cable is not plugged in to a router, or it may not be connected to the computer, or the network cable is not functioning.

Once I have checked the cabling and if the wired connection is still not functioning I will need to study its properties.

  • Right clicking on the wired connection opens a menu.  Choose Properties from the menu.
  • On the wired connection properties page you will notice the name of the network card is listed as well as any notification preferences you have selected.  In this case I have chosen to be notified when there is limited or no connectivity from the device. I have also chosen to be notified when the device is successfully connected.


The network notifications are shown on your task bar near the system clock as a small icon.

  • Now’s the time to check the network card and ensure that it is capable of obtaining an IP address.  You can do this by looking in the ‘this connection uses the following items:’ box for the TCP/IP option.  In the example below, you can see that TCP/IP is marked with a check mark.


  • Click on the TCP/IP item and then once it is highlighted click on the properties button below.
  • Now you will see the current TCP/IP settings for this network card.


The image above depicts the typical settings for a network card that is set to obtain its IP address from the networks router. At this point you should compare this setting to the same setting on one of the computers that is working.

If you find the functional computer has its TCP/IP settings set to a static IP you will need to use a different IP address (for the non functional computer) from the one on the computer that is working.

For example if the working computer is using you will want to use an IP address like Before choosing your IP address you should ensure that you do not use the same IP address that you have assigned to your network device (router). If all of your network devices including computers and routers are set to use static IP addresses you will need to ensure they are all close in numbers but none of them can be identical.  It is best to use IP addresses that are one or two numbers off from each other like the above example.

  • Now is a good time to restart your computer and access the Internet again once it is rebooted.

This should get your system up and running.

Here is a FREE easy guide to Computer Networks. Check it out.

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