Question Ethernet Speed - COMPLETELY out of ideas

Sep 24, 2020
Two desktops, both connected by ethernet cat6 cables. Paying for 1gb and am consistently testing at 200-400mbs. Updated all drivers, checked for windows updates, replaced both cables, checked for updated bios, uninstalled and reinstalled drivers, had spectrum come test their lines and they say they found no interference, still replaced modem to be sure. Below is the hardware:

-Gigabyte z390 aorus pro (not wifi)
-32g Corsair RAM 3000
-EVGA gtx 1070
-1tb ssd & sshd
-asus rt-ax82u router

Any help or direction would be greatly appreciated. I'm all out of ideas short of trying a new pcie ethernet port. (But what are the chances of having two separate pcs with ethernet port issues?)
Factory reset your router and only configure the admin and wifi passwords. Using many feature in routers disables a feature that allows nat to bypass the CPU. This many times will limit your speed to the rates you are seeing because the cpu in a router is so small. When you have very high speed internet connections pretty much consumers routers can only do the NAT function and not much else. You would need to use PC or something with a big CPU to do many of the functions.

Try a old program called IPERF on both your machines. The lan ports on the router are a simple switch so you should be able to get in the 900+mbps in both directions. This will rule out the machines,cable etc as the cause.