zzzwabbit

OK! I finally figured it out. There is something in the windows 10 Creators Update that messes with the congestion settings it uses and once i reverted to pre-cu settings i have no problem getting a 500Mbps reading from testmy.net!

You just got 109mbps? Maybe the discrepancy in speed can be attributed to your computer or Netflix streaming or traffic shaping on the router then.

This wd mynet n900 doesn't appear to be very powerful and it's advertised as using traffic shaping. Most likely 60mbps is its max throughput. You can try to turn off the traffic shaping and other unnecessary software on the device and see if that allows you to reach 100mbps. If you're happy with everything otherwise, just downgrade your package to match your max throughput.

1) are you on wireless?
2) what is the brand and model number of your router?

I am unable to get a reading over 50Mbps at TMN. The line is straight across and the speedof.me test shows a similar cap. speedtest.xfinity.com and speedtest.net show similar results.

When i test from a (brand new) m5.large instance to my home router using iperf, I see a solid 480 Mbps, the max for this speed tier (400 Mbps).

My only conclusion is that somehow traffic from xfinity to TMN is throttled. Is anyone with xfinity seeing this behavior?