I know this is an old thread, but I experience just that on my PC, a high middle speed variance.
I know it is not my router or internet connection, because all other devices and even my phone on Wifi will give me a down speed result double of my PC.
I have inserted the HDD from my son's PC, which is the same OS as I have, in my PC and then I also get a high download.
Since have I already reinstalled OS several times, tried other OS and other HDD's, but I always get the high middle variance ( +100% by the way)
FYI on all my devices connected over
