Internet download speed limited to 200 Mbps after fresh win installl

Win 10 Pro
Asus RAMPAGE IV Extreme motherboard/ 3960x cpu/ 32gb RAM/ GTX 1080 x2 sli
Intel 82579V gigabit onboard LAN

Upgraded to 1 gig internet, which was working fine, then decided to update firmware, secure erase my ssd's and reinstall WIN 10 to get the drives back up to speed, which all went fine.

Now my internet DL speeds are capped at 200 Mbps, but I was getting 990 Mbps before the WIN reinstall. I have tried multiple LAN drivers, as most search results of similar problems come back with 'installing the LAN driver fixed it.' Installing the drivers did not fix it.

I have tried the driver from the ASUS website and from the Intel website and tried just not installing the driver and let windows do it. I have tried installing and not installing the chipset drivers. I have tried doing all these things in different orders. I have tried reinstalling on different hard drives.

I have tried different ethernet cables. Tried messing with multiple settings in the advanced properties of the network card in device manager to no effect. Link speed shows 1 Gbps Full Duplex, passes all diagnostics.

Strange thing is if I do a speed test from Netflix it shows 1.2 Gbps consistently. Anywhere else the results are mixed and the more times you do the test the closer it gets to 200 Mbps. If I try to download a file from anywhere or install something through Steam, Blizzard app, or the windows store its all capped at 200 Mbps (20-25 MB/s) Other devices on my network are getting the full internet speed.

I am completely out of ideas here.

Hi, if you consider simply your disk transfer rate, independently of a download, can you be sure there's no constraint or limit there?

When you reinstalled Win 10, did you install the same build as was previously in use?

Shouldn't be related to your DNS.

Could be a difference in drivers - as you've tried- or settings, of course.