I should know how I did the last time I installed OpenWrt to my ASUS RT-N56U A1, but i don't(sorry).
According to the guide, [https://openwrt.org/toh/asus/rt-n56u#installation](https://Asus RT-N56U installation), I should "Download & Install the asus Firmware Restoration” from asus website". But I can't find it. I only find the the latest firmware for the router!
