I tried booting off Ubuntu, and my speeds were insane!Do you have another pc type device that is connected via ethernet. The goal would be to test inside your house between 2 devices and see what you get for transfer rates and compare that to the speedtest numbers. There is a old line mode tool called IPERF3 that can be used to test transfer. You could i guess use a file transfer and watch the numbers in resource monitor, just be aware some numbers in resource monitor are BTYES/sec and other BITS/sec.
You could try a USB bootable linux image. This will not damage your windows install. Most images have a browser preinstalled and you can run the same speedtest you do in windows. This is mostly to confirm it is some strange issue with windows driver or configurations. If the linux image has the same slow issue then you more suppect hardware.
914 down 38 up, so something in windows is likely slowing down my network.