Well, because internet companies now sell internet based on Mb/s, so if the reading is showing KB/s in HWINFO, it makes it difficult to get them to lower your payments due to you not having accurate proof of their shortcomings.
The nice thing about your situation is you can easily swap parts to find the culprit. However, I had a similar experience many years ago that damn near drove me crazy, and after all the buying new stuff and changing parts here and there, it turned out to be the power/reset switch on my case...