You’ve jotted down the hardware IDs: 21 , B6 , E1 , E2 .
If you go to downloadcenter.intel.com and search for "DP55KG LAN driver," you will find broken links or a redirect to a generic "Intel Ethernet Adapter Complete Driver Pack."
For everyone else ( 21 , B6 , E1 ): Instead, download the "Intel Ethernet Adapter Complete Driver Pack 25.0" from the official Intel Download Center Archives. Extract it. Run DevCon.exe to force the installation.
Modern Windows 10 and 11 have native drivers for many of these chips, but Windows 7, Windows 8.1, and even freshly installed Windows 10 LTSC often miss the specific INF files for the 15E2 or 15B6 variants. How to Download the Correct Driver (The Safe Path) Do not use "driver updater" software. Do not trust the first "Driver Download 2025" link on Google. Here is the engineer’s method. Step 1: Identify your exact Windows version (32-bit vs 64-bit) These legacy boards often require specific driver signatures. Most of the 21/B6/E1/E2 chips are 64-bit capable, but if you are running an old 32-bit OS, your options shrink dramatically. Step 2: Go to the official source (Intel’s Archive) Intel maintains a legacy driver repository, though it is hidden. Go to Intel Download Center and search for "Intel Ethernet Adapter Complete Driver Pack" .