I made a small Ndis2 inf-file for personal use. You can try. It works for me in case of Realtek RTL8111DL and RTL8111E. As I only have a 100 Mbps LAN, I cannot test the 1000 Mbps LAN that should be possible according to Realtek.
Although I think ragnargd don't need a HOWTO anymore , maybe others.
Installation instructions.
1) Find "Realtek NDIS2 driver ( Support DOS MSclient,Lantastic,Lanman,Norton Ghost )" on Realtek's Global site. Download will give you 0002-RTGBND2.152_EXE68.zip. Unzip RTGND.DOS and place this file together with my inf-file in a directory of your choice.
2) If Windows detects during boot-up "PCI Ethernet Controller", follow Windows installation-wizard. In case you already have a yellow exclamation marked "PCI Ethernet Controller" in Device Manager, choose "Install again".
3) After reboot, first go to real mode. If everything is all right, you will see during boot an installation-screen of the driver with "Link speed: 1000 Mbps" and "Duplex mode: full-duplex". On the MS-DOS command-line "mem /a/c/p" will show RTGND, PROTMAN and NDIS2 in conventional/upper memory. RTGND will take 42kb of memory!
4) Type "win" and go inside Windows to Properties of Network Neighborhood and look for "RTL8168/8111 PCI-E Family Ethernet Adapter". Properties will show that there is a "Real mode (16 bit) Ndis2-driver", choice of other drivers is grayed out. Bindings shows TCP/IP and Advanced will show only Link Speed choices. Default is "Auto Detect", other possibilities are "1000 Mbps full-duplex", "100 Mbps full-duplex", "100 Mbps half-duplex", "10 Mbps full-duplex" and "10 Mbps half-duplex". During reboot you will see your choice in the MS-DOS installation screen of the driver.
There is one small drawback in using this real mode Ndis2-driver. After "Exit to MS-DOS" you cannot return again to Windows and using the driver. The driver needs always a full reboot. It should have to do something with flushing the cache of the NIC
So don't mess around with Config.sys, Autoexec.bat or Protocol.ini. Let the Windows Installer do the job.
Please report your findings. WARNING: you make this installation at your own risk, no warranty at all!
NetrtgRM.inf