If you cannot see -5Ghz on your adapter for the WiFi.. it's either your setting Wrong or Adapter cannot take it.
Check if you set the band correctly
WiFi> Change Adapter Settings >> Properties >> Configure >> ADVANCED TAB
This will configure your WiFi to correct band as the ASUS N56 or N66 has 5Ghz
Next up is your settings
Go to the router, and check for the Channels.
Don't use AUTO, but if you happen to do so, it's either these settings. Firmware shown here is the LATEST STABLE VERSION.
So match these frequencies.
Because my PC is Kapoot.. it's useless..
So have fun!