Firmware Upgrading Instructions by ASUS RT-AC1200, Download firmware and Firmware Restoration software to be upgraded from ASUS website and follow steps below.
ASUS Firmware Restoration version 2.0.0.0 Download
ASUS RT-AC1200 Firmware version 3.0.0.4.380.9880 Download
Firmware Restoration is used on an ASUS Wireless Router that failed during its firmware upgrading process. It uploads the firmware that you specify. The process takes about 3 to 4 minutes.
IMPORTANT: Launch the rescue mode on the router before using the Firmware Restoration utility.
NOTE: This feature is not supported on MAC OS.
To launch the rescue mode and use the Firmware Restoration utility:
1. Unplug the wireless router from the power source.
2. Hold the Reset button at the rear panel and simultaneously replug the wireless router into the power source. Release the Reset button when the Power LED at the front panel flashes slowly, which indicates that the wireless router is in the rescue mode.
3. Set a static IP on your computer and use the following to set up your TCP/IP settings:
IP address: 192.168.1.x
Subnet mask: 255.255.255.0
4. From your computer’s desktop, click Start > All Programs > ASUS Utility > Firmware Restoration.
5. Specify a firmware file, then click Upload.
NOTE: This is not a firmware upgrade utility and cannot be used on a working ASUS Wireless Router. Normal firmware upgrades must be done through the web interface.