I'm running firmware 3.13.34 Build 140127 Rel.64714n. I changed the wireless channel to 36 and left WMM on. I could not get the WIFI to connect to anything on my late 2013 Retina Macbook with WPA2...

Dominick wrote I was sent a brand new beta: https://dl.dropboxusercontent.com/u/87935752/ArcherC7v1_en_3_13_34_up_boot(140127).bin I have not tested it to see whether it fixed the 5GHz issue or not....