I also tried a factory reset of the RT-N66U router. Same problem: everything else can connect to the default open "Asus_5G" network except this computer, which can only connect to the 2.4GHz "Asus"...

Thanks for the suggestion! It doesn't seem to have changed anything though.

Model : Hardware Version : Firmware Version : ISP : Adapter: TP-Link TL-WDN4800 Router: Asus RT-N66U OS: Windows 10 After a Win10 update and reboot yesterday, I can no longer connect to my 5GHz...