ASUS RT-AC51U OpenWrt Firmware

CPU: MediaTek MT7620A
RAM: 64 MB
Flash: 16 MB

The ASUS RT-AC51U is supported by OpenWrt on the ramips/mt7620 target. 2 firmware images are available from the official OpenWrt 25.12.5 stable release — download one below, or build a custom OpenWrt image for this device with your own package selection.

Specs

Specifications

CPU	MediaTek MT7620A
CPU cores	1
CPU frequency	580 MHz
RAM	64 MB
Flash	16 MB
100 Mbit Ethernet ports	5
WLAN hardware	MediaTek MT7620A, MediaTek MT7610E
Switch	MediaTek MT7620A

Hardware data from the OpenWrt Table of Hardware; verify against your unit before flashing.

Build matrix

Supported firmware versions

Distribution	Version	Target	Profile
OpenWrt	25.12.5	ramips/mt7620	asus_rt-ac51u

Downloads

Download images

OpenWrt 25.12.5 · ramips/mt7620

Image	Type	sha256
openwrt-25.12.5-ramips-mt7620-asus_rt-ac51u-initramfs-kernel.bin Minimal kernel image, useful for first install or recovery.	kernel	c984f0430745…
openwrt-25.12.5-ramips-mt7620-asus_rt-ac51u-squashfs-sysupgrade.bin Not sure? Pick this if upgrading from OpenWrt.	sysupgrade	a81c325a889c…

Downloads are served by the official OpenWrt mirrors — unchanged upstream stable builds.

Packages & install

Default packages & installation

Default packages

Every image for the ASUS RT-AC51U ships these packages by default. The customize option below lets you add or remove packages before the image is assembled.

Device packages (4)

kmod-mt76x0e kmod-usb2 kmod-usb-ohci kmod-usb-ledtrig-usbport

Target default packages (29)

apk-mbedtls base-files ca-bundle dnsmasq dropbear firewall4 fstools kmod-gpio-button-hotplug kmod-leds-gpio kmod-nft-offload kmod-rt2800-soc libc libgcc libustream-mbedtls logd mtd netifd nftables odhcp6c odhcpd-ipv6only ppp ppp-mod-pppoe procd-ujail swconfig uci uclient-fetch urandom-seed urngd wpad-basic-mbedtls

Installation notes

Already running OpenWrt or ImmortalWrt: flash the sysupgrade image from LuCI (System → Backup / Flash Firmware) or with the sysupgrade command.
The kernel / initramfs image boots from RAM without writing to flash — useful for a first install or for recovering from a failed flash.

Verify your download against the published checksum before flashing:

$ sha256sum openwrt-25.12.5-ramips-mt7620-asus_rt-ac51u-initramfs-kernel.bin
c984f0430745e1ee4a0fa2e82f4c2b01746926397b0ea5e8faa2412bde7a3fc9  openwrt-25.12.5-ramips-mt7620-asus_rt-ac51u-initramfs-kernel.bin

Build custom firmware

Need more than the default image for the ASUS RT-AC51U? Pick your packages — LuCI apps, themes, VPN clients — set the basics, and get a ready-to-flash OpenWrt image assembled from official packages in minutes.

Customize firmware for this device

More ASUS devices

More devices on ramips/mt7620

Upstream

Upstream & source

Images are assembled from packages compiled and published by the upstream OpenWrt and ImmortalWrt projects. The complete corresponding source code is available from those projects under the GPL.