ASUS Router Cannot Login Unless Logout Another User First

When trying to log into the web console or administration page of ASUS router or wireless router based on Asuswrt firmware, including model RT-AC56U, RT-N66U, RT-AC66U, RT-AC68U, RT-AC68P, RT-AC87U, RT-AC3200 and their R and W equivalent, the following error message is shown and login failed.

Login user IP: <IP Address> (Computer Name)
You cannot Login unless logout another user first.

ASUS router does not support simultaneous login as security measure. So if you use the account to login in a computer or a specific web browser, you cannot use the same account to login again in another computer or another web browser until you logout the previous session.

However, if you have close all the web browser, or have signed out of ASUS router web interface, and the error is still happening, uses the following trick to reset the login session information on the router by erasing the information about login ID and IP address from NVRAM:

1. Connect to ASUS router via Telnet or SSH, and login as admin.
2. Run the following commands:

   nvram unset login_ip_str
   nvram unset login_timestamp
   nvram unset login_ip
   nvram commit

Telnet and SSH are disabled by default. If you did not enable them, the only way to reset the login and allow you to login again is to power cycle the ASUS router, by powering off and re-powering on.