Bought a brand new unit..after two days noticed the speed dropped considerably and the unit had 100% CPU 1 and/or 2. Hard reboot and the 2.4GHz band never came back. Asus support recommended downgrading firmware and factory resetting unit. Still, 2.4GHz band never came back. Device was 3 days...
Similar issue with a brand new ac88u on the latest firmware. All of a sudden internet slowed to a halt, 2.4ghz band disappeared. I did a manual power down and back up except my 5 and 2.4 bands turned on and off a few times then eventually disappeared. No wifi at all now..
Just out of curiosity...