BCM4321 802.11a b g n Driver 4.100.15.5

1. Create a restore point(Start → "Create a restore point" → Create), so you can roll back if anything goes wrong.
2. Verify compatibility: your Windows version (Windows XP) and architecture (x64, x86)must match this driver, and your device's Hardware ID should appear in the list above.
3. Download the file using the button - it comes directly from Microsoft Update Catalog.
4. Optionally verify the checksum: open PowerShell, run Get-FileHash your-download.cab -Algorithm SHA256 and compare with the SHA-256 above.
5. Extract the .cab archive: right-click → Extract All, or run expand -F:* file.cab C:\driver\ in Command Prompt.
6. Install via Device Manager: right-click your device → Update driver → Browse my computer → point to the extracted folder. Alternatively run pnputil /add-driver C:\driver\*.inf /install.
7. Check Device Manager: the device should show no warning icons, and the driver version should match.

If the device stops working after the update: Device Manager → right-click the device → Properties → Driver tab → Roll Back Driver. If the button is greyed out, use the restore point from step 1 (Start → "Recovery" → Open System Restore).