Asuswrt-Merlin 386. But Asus added a check to its latest 3. Download Center | Official Support | ASUS USA. Feb 03, 2017 · Firmware-update: Asuswrt-Merlin 380. All good for a week rock steady on all devices getting a good 60 to 80mb all day and night. We have used Asus RT A68U router flashed with Asuswrt-Merlin firmware for demonstration.