I have a few E3200s and I can reliably screw up the 5GHz wireless. When I change the web admin local access from HTTP to HTTP & HTTPS, 5GHz will disappear from the GUI and persists after reboots. Sometimes I can get it back by unconfiguring HTTPS, but sometimes not. Strange behavior. I don't have the same issue on Asus RT-N66, only Linksys E3200.