for my WRT1900ACv2 and it hit 1300Mb/s as soon as the settings updated. I have followed those same directions for my Nighthawk and I have never seen it get past 400. I have been hammering on this for over a week and I am at a loss. I upgraded to the most recent firmware when I got nowhere last week with a year old version and I am continuing to have no joy this week with the new version 43324. I have flashed the new version 3 times because that seemed to do the trick last time I wrestled with this piece of equipment. Weirdness I have noticed is that the Wireless Channel reverts to Auto after I set it (attached) according to the Basic Settings guidelines. I have also included a snap of the security settings which seem to conform to the guidelines.
With your steps below, I seem to be unable to get the correct Channel + Extension combinations specified in the basic settings. When I select UU in step 2 for example, the list of channels available in the drop down is the list of channels recommended for pairing with LL according to the basic settings. For all three of the extension channels noted in your step 2, the list of available channels is a list of the recommended channels for the opposite extension channel. Following your steps has bumped my rate up to 702 Mbps but still not 1300.
Any other suggestions for what I might be missing?
I am pleased to say that setting the channel to one of the 136+ channels immediately caused the rate to change to 1300 in the sys-info tab. This is true with or without any clients connected and with or without a WAN connection.
Might it be worthwhile to update the Basic Wireless Settings to note this?