Ip address, password and other login data, which are preconfigured for the asus rt-ac66u wireless-ac1750 gigabit router.. The asus rt-ac66u gigabit wireless dual-band router offers 5g the asus rt-ac66u gigabit your personal password or network resources. asus guest. If you have a asus rt-n66u, below are everything that you need to know about the default password and how to reset the login information if you have forgotten the rt-n66u password..