RAX15 slow internet speeds with Macbook Air

I have severl netgear routers in my home.  All are set up as access points.  All of my windows conputers connect and speed test at very high rates to all of these APs.  That said, my macbook air only downloads at a 27 MBPS rate when connected to 5GH radio in my RAX15 when 2 feet away from the access point.  It connects at respectable speeds to all of my other Netgear APs.  None of my other apple products have the same problem.  For example, my Ipad runs at 350 MBPS when connected to the RAX15.  If it helps the macbook is connecting using the 802.11ac protocol.  Anyone solved this problem.  One last thing - I have downloaded the latest firmware for my RAX15 and it did not help

Thanks