The Asus AC66U (no B1) was originally a draft AC router using the same CPU chip and plastic housing as the Asus RT-N66U just with an additional AC radio. Asus then upgraded the router by using the exact same hardware as in the Asus AC68U 1900 AC router and placed it in the new AC66U B1 router while still using the old plastic housing.
Developed by Eric Sauvageau, the Asus-Merlin is an alternative firmware offering users more customization (control) over the stock firmware by ASUS. Asuswrt-Merlin - Custom firmware for RT-AC66U Aug 18, 2012 How to set up and optimize an Asus RT-AC66U - The Silicon
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Jan 07, 2018 DD-WRT Forum :: View topic - New RT-AC66U Hardware Apr 01, 2017
May 24, 2017
None: Remote: Medium: Not required: Complete: Complete: Complete: Global buffer overflow in networkmap in Asuswrt-Merlin firmware for ASUS devices and ASUS firmware for ASUS RT-AC5300, RT_AC1900P, RT-AC68U, RT-AC68P, RT-AC88U, RT-AC66U, RT-AC66U_B1, RT-AC58U, RT-AC56U, RT-AC55U, RT-AC52U, RT-AC51U, RT-N18U, RT-N66U, RT-N56U, RT-AC3200, RT-AC3100, RT_AC1200GU, … Asus RT-AC1750 - New/locked down version of RT-AC66U? - DD … Jan 07, 2018 DD-WRT Forum :: View topic - New RT-AC66U Hardware Apr 01, 2017 How to Install the Asuswrt-Merlin Custom Firmware on an Aug 03, 2013