FTP transfer speed dropped from 100MB/s to 2MB/s

I recently upgraded my motherboard from Asus Crosshair IV Formula to Asus P8Z68-V PRO/GEN3.

I had previously configured my home network to fully support 1Gb transfers in LAN between my desktop and my laptop. I could transfer files with full 1Gb speed via FTP and Windows file sharing.

But now with the new mobo and it's new network adapter my FTP transfer speeds have dropped down to 2MB/s meaning both upload and download speeds. Windows file sharing still works fine and I can achieve 50-100MB/s speeds with it.

What is causing the FTP to work so poorly now? I can only assume it's the new network adapter since it's the only thing that's changed. I have installed the latest drivers, ran all diagnostic tools the software included, enabled and disabled every feature in the driver configuration but nothing has worked.

I've also tried all the guides I've found online like disabling Remote Differential Compression with no success.

How could I achieve normal speeds with FTP file transfer again?

Bump

I just did a fresh install of Windows on my desktop and the problem still presists. I guess the Intel Ethernet adapter just sucks.