Horribly slow internet on new build Windows 10 Pro

[Shoktronic]

I need some serious help here!

I finished a build using the Asus Crosshair VIII Hero motherboard.

My internet speeds on BOTH ports are only getting to 100Mbps. I have tested the same cable/connection on two other Asus motherboards ALSO running Windows 10 Pro and they are getting 500 Mbps+. My provider speeds are 1 Gig down and 30 Mbps up. My upload speed is fine at 30 Mbps.

I have removed almost all other software from my computer to include the Asus software for RGB. I have tried everything listed on the internet to include Powershell tweaks, TCP Optimizer & updated drivers from Intel. NOTHING is fixing this and its not an issue with any of my network equipment.

WTH is going on? Just trying to log into this forum was a nightmare!

I need help for the love of all things please!!!!

Chris

[samx77]

Hello mate,

Did you find any solution on this? I have very similar problem asus x670e-e MB, amd 7800x3d. My link speed shows 1000 Mbps I have 1 gig fiber connection in my home but speed test cannot go over 100 mbps. Why is that happen? Same cable directly from router works on laptop 1000mbps but my desktop internet speed stucked in 100mbps even if link speed shows 1000mbps in Windows and on Ethernet controller settings.

[Troubled42]

Feel like I have the exact same problem but on an X570-F. 
Rebooted into safemode and speed tests are around 700-770mb to rule out anything else leeching the connection.

A laptop on the same cable gets 1Gbps...

uninstalled network drivers and downloaded latest from Intel, no difference.

[Troubled42]

Fixed....

I had  Window Auto-Tuning disabled (probably to fix something else not working!). Re-enabling it made me go back to 1GBPS speeds...
details on the commands to run below.

https://www.ghacks.net/2016/08/05/windows-10-limiting-internet-speed/

[Murph_9000]

That makes a lot of sense.  Original/unenhanced TCP is designed for a world when 10Mbit was normal LAN speed and 100Mbit was fast.  The various enhancements/improvements to TCP over the years are essential to getting it to perform in a gigabit world.  Window size was one of the major limiting factors in the original design.