I just installed a replacement router (Asus RT-AC68U-1900). I set up my old Linksys ea6500 as an AP. Using InSSIDer 4.0 I was getting max rates on the 2.4 at 450 and 5Ghz at 2106. Then I upgraded to the latest version of IS 4.0 (4.2.109) and my max rates went down in half.

Here is what I am getting:
ea6500 (AP):
2.4Ghz; ch 1; bgn; 450; 5.0ghz: ch 157/155; n/ac; 1300

AC68U:
2.4Ghz; ch 11; bgn; 216.7; 5.0Ghz; ch161/155; n/ac; 1300

I am getting better max rates with the AP ea6500 on the 2.4Ghz. Any ideas?