There is a registry key under HKLM\SYSTEM\CurrentControlSet\control\Class\{4D36E972-E325-11CE-BFC1-08002bE10318}\00xx that can be set to  cause the driver and chip not to strip the 802.1Q headers. In order to set that key, you need to find the right instance of the driver in Registry Editor and set that key for it. You  can do this by doing following:

1.    Run the Registry Editor (regedit)
2.    Hit CTRL+Home to go to the top of the registry
3.    Hit F3 to bring up a search
4.     Search for  TxCoalescingTicks - actually a search for txcoal will do

This should take you to something like:

5.    Right-click on a bit of white space near the TxCoalescingTicks field.
6.    Enter "PreserveVlanInfoInRxPacket" –
a.    Then highlight the text PreserveVlanInfoInRxPacket and copy it to the clipboard – you’ll need it again later.
7.    Give the newly created field (PreserveVlanInfoInRxPacket) the value "1".
8.    Hit F3 to repeat the search – goto step 5 again.  Repeat until you reach the beginning again.

9.    Reboot the PC