Accessing the Asus RT-AC66U login page is the key to customizing your router settings. Firstly, turn on the router and connect your device to the router's network. Next, open a web browser and enter “ http://www.asusrouter.com/” in the URL bar. Next, on the login page, enter the correct username and password. Now, click on the sign in, and you are good to go.
https://www.asuslogin.com/asus-rt-ac66u-login-for-seamless-connectivity/