|Those were common and reliable chipsets. If you are sure you have the correct drivers for the onboard NIC (which you would have to get from Dell, not anywhere else) then the onboard network interface itself may be bad.|
If however, you got the drivers from elsewhere (ie: other than Dell) then you're not taking into account the proprietary nature of a Dell (or any other brand name computer) who's hardware, even when using common brand name devices, often did not work properly with drivers from anybody but the manufacturer of the computer itself. I even had issues with hardware downloading the correct driver from the device manufacturer when it was a brand name computer.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.