latest firmware is full of bugs. and wifi issues is one of them
many bros here had to exchange their routers because of it!
bro, better downgrade to 2345 and hope your router is not giving you issues after the downgrade, if it is, you go to avertek and swap for a new unit and DO NOT UPGRADE
Download the ASUS Rescue tool
http://dlcdnet.asus.com/pub/ASUS/wireless/RT-AC88U/UT_Download_Master_2228_Win.zip and Firmware version
http://dlcdnet.asus.com/pub/ASUS/wireless/RT-AC88U/FW_RT_AC88U_30043802345.zip
Power off your AC88U with the power button
Hold down the red reset button ( with a pen)
Turn on your AC88U while holding the reset button (20 Secs)
keep holding until you see the Power LED Blinking, after that release the reset button and if the LED is still flashing, it means your AC88U is in rescue mode
So, connect a LAN Cable to your AC88U and the other end to your PC
set the IP of your PC to 192.168.1.10 and the rest is default (255.255.255.0)
Open up the ASUS tool and upload the FW
Wait for it to finish and it will restart your router
Set your IP Back to DHCP and you should be able to access the GUI Page
AC88U Users, DO NOT UPGRADE TO THE LATEST FIRMWARE VERSION!