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Please Help Me Understand Xfinity Speed Test

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Please Help Me Understand Xfinity Speed Test

I'm having trouble understanding this.

  • Xfinity Speed Test : 123.9Mbps
  • 86.3Mbps
  • Google's Speed Test: 75.5Mbps
  • Speakeasy Speed Test: 89.9Mbps
  •'s Speed Test: 84Mpbs

Now that all seems reasonable, right?  But during all of the tests I'm recording the total bytes per second as reported by Windows using the built-in typeperf command.  The same values are available using the Performance Monitor tool.


These tools show that the maximum bandwidth of my wireless adapter is 99.25Mbps.  During all of the tests, the tool also reports the actual number of total bytes sent and it never exceeded 11781116 bytes per second.  That's 94.2Mbps.


Also, when I copy a file my NAS device, the maximum speed achieved was 12010194 bytes per second.  That's 96.0Mbps.


Can someone explain how it is possible that I'm able to download from XFinity at 123.9Mbps when every other test is below 99.25Mbps, Windows reports my device as maxing out at 99.25Mbps, and during the test Windows reported a maximum speed of only 94Mbps during the test, and copying a file from my NAS device maxes out at 96.0Mbps.


Obviously, the limiting factor here is my wireless adapter on this PC.  My NAS can copy files much, much faster.  


I just don't understand how Xfinity can achieve 123.9Mbps?


The command I'm using is:

typeperf "\Network Interface(TP-Link Wireless USB Adapter)\Bytes Total/sec" "\Network Interface(TP-Link Wireless USB Adapter)\Current Bandwidth"