In order to update the firmware of the Asus RT-N12E router, you need to enter its settings by typing in the browser address http://192.168.0.1 and enter your login – admin, password – admin, see the firmware version that is installed, usually it is written at the very top, for example “Firmware version: 126.96.36.199”.
Check for a new version of the firmware on the official site http://www.asus.com/Networking/RTN12E/HelpDesk_Download/ and if it is there to download it.
Next, open the menu “Administration“, select a tab “Firmware Upgrade“, press “Browse” and select the firmware file, click “Send” and wait for the update process to complete.
The configuration of the router remains unchanged.
If the update fails, the router can be restored using a utility that can also be downloaded from the link above.