I'll try to post a tutorial here in the near future (at least in English).
Well, I did it some time ago:
viewtopic.php?t=27572 (I'll probably have to do a French translation too at some point…)
You might be lucky, there is a PCI-E NDIS2 driver from 2012 and your NIC is from around that time. (This driver might work with newer chips also, the NDIS2 driver from Intel is universal -> works with all gigabit cards, and there is a separate driver for all the 10/100 cards)
ATNDS2.DOS
Atheros PCIE Ethernet Controller NDIS2.01 v2.1.0.10(09/11/12)
Check out this great and simple site:
http://packetdriversdos.net/
Since tethering is rather a pain, I decided to get a powerline adapter I had lying around and try this out. I was able to follow
the NDIS instructions but I had to get the MSCLIENT stuff from
the Internet Archive because I couldn't get at ftp.microsoft.com
Then it turns out that that NDIS driver only supports cards with ID 0x1090, 0x01091, 0x10A0, or 0x10A1, whereas mine is E091h. This wasn't really a problem because I could change the byte at offset 0x19, from 0x10 to 0xE0. But then, the whole thing freezes my system due to an IRQ conflict with the hard drive controller. Yes, apparently that can happen in 2022, with PCIe devices!

(I guess that's what you get for using DOS in 2022!

) I'll keep at it and see if I can solve the problem…