Need help installing OpenWrt on asus RT-ACRH17 REV 1.60 aka RT-AC42U

need help installing OpenWrt for the first time on an asus RT-ACRH17 REV 1.60 router that still has the factory firmware installed. This hardware is listed as supported and the same hardware as the RT-AC42U model router. I tried to install using the stock firmware upgrade method from the webGUI but the openwrt file was rejected as a bad firmware file (I suspect it's signature may not have matched or somesuch. ) I moved on from there and have now most likely voided the asus factory warranty by removing the 4 screws from the bottom, destroying the tamper tag on one screwhead, carefully removing the top cover, and connecting to those so nicely labeled pins on the circuit board labeled GND, RXD, & TXD with a FTDI 3v3 USB to TTL serial cable.

I now have serial console access! How can I install a working OpenWrt Firmware on this device... possibly even booting from a usb thumb drive or maybe TFTP into ram first then flash.

The serial bootlog follows and appears to give some options.... but please, the implimentation is in the details and i need help with those details as to what to do from here:

full bootlog here:

the boot commandline interface (option 4) has a few interesting options like boot from USB that could be useful, but how would i sertup the usb stick for this option.

the other options for TFTP look useful but how do i use this and TFTP to load firmware.
do I need to setup a TFTP server or client to host the firmware
how is the TFTP process done

finally there appears to be a serial option. how would I install over serial.

when successful here, I'd like to setup a support page for these units to help others.

Your specific device is not supportedby OpenWrt, as you probably already know.

Is it actually an identical device (with different model designation for whatever reason)? Just having the same hardware doesn't actually mean it is the same design. Before you go much further, you should verify that is truly the same down to the circut design level. If it's not, there is a chance that you could brick your device.

EDIT: nevermind what I said... I missed the comment on the device page that says they are equivalent devices.

here's the firmware for it:

how is it not supported

this says it is:

what am i missing

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If you got serial access, go into cli mode in u-boot, run tftpboot, then bootm while serving the initramfs image via TFTP.

Ah... I stand corrected. It is a very small note at the bottom of the page that I missed.

Comments:aka RT-ACRH17


Could you explain a bit further. Do I need to setup a tftp server or use a tftp client on another computer. how exactly do I serve the file to the router

Server, on some computer connected to the router.

I just hope the device is using uboot and the two commands are available ,)

no problem, we all miss stuff occasionally.


Use the asus recovery tool. Hold reset for a few seconds while you plug in power. Most probably fast blinking lights or similar will indicate it’s in recovery mode. Then press send (or equivalent) in the restoration app. (Dont neet to set static ip)

He'd seen it over serial though, wouldn't he ?

where do i get this asus recovery tool

Check at the bottom.

Oh I see it’s an ipq40xx.

I’m gonna bet you need to follow the same steps for flashing the Asus Lyra.

I don’t know if OpenWrt and OEM differ regarding UBI partitions like the Lyra, but if it does then you need serial and tftp for unbricking. (Also I don’t know if uses HIVESPOT.trx for the tftp filename, but you can always save the first MTD and poke around it and update the OpenWrt TOH page if you find out.

well, the recovery tool just became a non-option.... probably works well for windows users but i am unable to try it as i have an older mac running osx 10.13.6 high sierra (linux via raspberry pi is likely also available). OSX comes with a TFTP server however, so on to that method via serial console.

just to double check before I TFTP the wrong file onto the device, thus bricking it, which of the following files should i serve via TFTP?:






but i'd like to double check before bricking the device.

Correct. Install then sysupgrade file afterwards

I have the same model router. I also have the recovery tool on windows that I used yesterday to flash freshtomato on another asus model. Do I just put the acrh17 into recovery mode and upload the 2 image.itb then sysugrade and I should be good?