Could only get my usual 135Mb when connected to my Nighthawk R8000

[MarkBC]

This solved it for me.   Just today I upgraded from 150Mb service to 1Gb service and while my MacBookPro could see about 930Mb when connected directly to the modem, it could only get my usual 135Mb when connected to my Nighthawk R8000. 

I tried the solution "have nothing but a single Gb switch connected directly to the router", but that didn't help.  What did fix it for me was turning off both toggles on the Nighthawk QOS page ( "QOS" and "Automatically update performance optimization database").  Turning them back on and the problem reappears.  Turn them off and the problem is gone.   I also happened to go into the Network / Advanced / Hardware settings of my MacBookPro (and my wife's iMac) and changed the network speed setting from Automatic to 1000Mb, but I don't think that mattered.

My setup:   MacBook Pro (wired), iMac (wired), and MacBook Air (wireless) connected to the Nighthawk R8000 router, connected to a Hitron CODA-45 modem, connected to 1Gb cable service.  I also have a D-Link DGS-105 1Gb switch (for the TV, Apple TV, and computer games) connected to the Nighthawk, which is how I was able to do the "use a Gb switch only" test.  All cables are "Cat 5E".

Interestingly, with QOS off, the first SpeedTest.net test gets 900+ Gb, but some subsequent tests come in around 650 Mb.

[plemans]

Also make sure that parental controls, access controls, and traffic monitoring are disabled. 

Those services and qos all disable ctf (cut through forwarding). CTF is needed to hit gigabit speeds. When its disabled, the processor has to analyze the traffic but the processor doesn't have the capability to do so in realtime. Which is why speeds slow