Model :

Hardware Version :

Firmware Version :

ISP :

So, after much time spent reading and g00gling around, trying all Atheros drivers with no luck, I finally found a 100% working solution to make this adapter work under Windows 10 x64 (hopefully the same can be applied for Windows 8.1), although it's not compatible with this OS.
Here's the picture:
Adapter: TL-WN851ND, ver 1.0, OS: Windows 10 x64, MB: Gigabyte GA-B250M-D3H
I installed Windows 10 x64 on a brand new 7th generation Pentium and a new board with B250 chipset. At first, when I started Windows installation, the adapter was inserted. Windows froze every time while the card in PCI slot. After removing it, everything worked. At this point, Windows probably installed its own driver and freezes every time. Solution for this is to remove the adapter, start Windows, go to Device Manager (Windows key + R -> devmgmt.msc) and once there, check the Network adapters. Of course, while adapter is removed, it won't be listed there, so click View -> Show hidden devices. Adapter should be listed there, so uninstall it by right clicking on it and click Uninstall (believe me, it won't hurt). Shut down Windows, insert the adapter and run Windows. It won't try to install the driver again, nor will detect the adapter. Next, download the only driver available from http://static.tp-link.com/resources/software/TL-WN851ND_v1_110825.zip
, unzip it somewhere. Now at this point: do not use the installer, but search inside "Driver Files" folder, browse to Windows 7 32bit or 64bit, depending on your OS installed, right click "netathr.inf" or "netathrx.inf" (again depending on the OS) and click Install.
Do not use any other drivers as the result will be always the same (at least for me every time) - Windows will keep freezing.
Do not update the driver under any circumstances as it will lead to the result, mentioned above.

Voila.
You should now have the adapter installed and ready to go.