In Vista, TCP Window Scaling is enabled by default. If your router does not tolerate this feature, it can cause random DNS and connection errors. This is a common cause of Vista limited connection errors.
Microsoft’s Vista enables a TCP Window Scaling option by default. For most systems, this is a good thing. However, if your router does not tolerate this feature, it can cause many connection areas on your network. This conflict will cause drop packets and limited connection in many circumstances.
If you try to diagnose this problem, you may see a window that says that Windows Network Diagnostics “Cannot communicate with Primary DNS Server.”
To fix this problem, you should do one of two things. First, just upgrade your router to take advantage of this new feature. Second, you can just turn off this TCP feature.
I am sure there is an easier way to turn off this TCP feature. I just do not know it. Here is how I have been doing it:
1. Connect to your network on your troublesome Vista box.
2. Click on this link while your network connection is working:
3. Click the link that reads Diagnose Connection Problems.
4. You should see something like this:
5. Click the button that says Turn off the TCP setting that is not compatible with your router.
6. Allow the repair to take place.
If it works to fix your system, you should notice that your episodic connection problems disappear.