Connection Problems

Diagnosing Net Connection Problems
By Ronald Pacchiano
-------------------------------------- Professional Edition
Vol. 4 Number 44
October 29, 2003
1. NIC, cable, router port
2. Reinstall the CP/IP stack- remove all network adapter drivers, remove all communication protocols (TCP/IP, IPX/SPX, NetBEUI, network client. Reboot. Reinstall the network adapters. Reboot again.
3. Check for viruses
4. Do a clean install of Windows (FDisk, Format, Install Windows)

Diagnosing Net Connection Problems

Have a network with one or two PCs that can't connect to the Internet or other networked computers? We look at several tips and tricks of the trade that could help you diagnose and fix computer connection issues.

I have a small network made up of four computers. All of the computers are connected to a NETGEAR DG814 router via Ethernet cables. Three of the computers on the network are set up and working fine, but I'm having problems with the 4th computer, a Sony VAIO PCG-FX103 notebook.

For some reason the VAIO is incapable of seeing any of the other computers in the workgroup or browsing any websites. I can't even "Ping"
( the router from the notebook. I'm fairly sure the cable is good because the light on the card and the one on the router itself are both illuminated.

One strange thing I did notice however was that WINIPCFG was reporting that the PC is using an Internet protocol (IP)
( address beginning with a 169. My router's dynamic host configuration protocol (DHCP)
( scope is supposed to be assigning IP addresses of 192.168.0.x. I tried manually setting the IP address to, but that didn't help. I've tried as much as I can think of (renewing IP address, adjusting settings, etc.). Do you have any ideas what else I might try?

I'm not surprised that the system didn't work even after you manually entered the correct IP address information. Typically the only time you would get an IP address beginning with a 169 is when the PC is not communicating with the DHCP server. So if it's not communicating with the server, entering the correct information isn't going to help.

There are a number of reasons why this might happen, with the most obvious being a physical problem with the network adapter itself. Just because the link light is lit doesn't mean the card is working properly or that the cable is good. Also, you could try moving your cable to a different port on the router. Ports don't go bad very often, but it is a possibility.

Now if you're on a wireless network, there could be a million possible causes for your problems. However, since you are simply connecting a single PC to a router via an Ethernet cable, the possibilities are much more limited.

In my experience, when this situation comes up, the majority of the time it has to due with some type of problem with the transmission control protocol/Internet protocol (TCP/IP) stack. Usually some aspect of it has become corrupted, and the entire stack needs to be reinstalled as a result. The process varies from one operating system to the other, but basically what you would need to do is go into your network properties and remove all of the networking components that are installed there.

This usually includes things like the Network adapter drivers, the various communication protocols (e.g. TCP/IP, IPX/SPX, [] NetBEUI []), and the network client. Once all of these items have been removed, you'll be forced to reboot the system. After the system reboots, reinstall the network adapter drivers, which should also install any additional components you might need. After the system reboots again, your TCP/IP protocol stack should be functioning correctly once again.

One thing you might want to consider doing before all of this is to verify that your PC hasn't been infected by a virus. There are numerous viruses out there that could disable your PC's communication capabilities, so I would recommend first downloading the latest virus definitions and thoroughly scanning your system.

If all else fails and neither of these suggestions work, you might have to consider wiping out the PC and reinstalling the operating system. Sometimes a Windows system can become so saturated by poorly written software (not to mention things like adware and spyware) that it can just become completely unstable and have a detrimental effect on the performance of various systems. Sometimes this includes network communications. While I admit that it is a major hassle and inconvenience to redo it, I can almost guarantee that it will solve your problem.