I am keen to use OpenWrt on my Asus Lyra map-ac2200 but before doing so,
a) I would like to ensure I can return to stock firmware at a future date. Can this be done? If so, how and does it work?
b) the instructions for installing OpenWrt map-ac2200 https://openwrt.org/toh/asus/lyra_map-ac2200 require running the sysupgrade command, however this command does not appear to be part of the firmware. Is this command deployed in the .itb write or is it already in the stock firmware. In the case of stock firmware, what version of stock firmware do I need as it is not in my current running stock firmware?
For this device, it's a two-step process, you first flash the OpenWrt initramfs image using the OEM firmware's mtd-write, once you've rebooted into this OpenWrt initramfs image, sysupgrade will be available and needs to be used for step two.
After hours of tinkering, I have finally figured out how to restore factory firmware on the Lyra MAP-AC2200! I take no credit for this, it is essentially the same as for the RT-AC58U. I will update the wiki when I have time but here are the cliffnotes:
We need to follow the instructions for the Asus RT-AC58U here https://openwrt.org/toh/asus/rt-ac58u#returning_to_stock
With the caveat that the instructions do not work for OpenWRT 22.03.0, and above: https://github.com/openwrt/openwrt/issues/9879
As usual with things like this, I take no responsibility for anything that happens by following these instructions.
Steps:
Connect your computer directly to your router using the ethernet port directly beside the DC plug
Downgrade OpenWRT firmware to 21.02.3 via web interface, reset settings: Firmware link
Login to 192.168.1.1 via SSH
execute 'ubirmvol /dev/ubi0 -N linux2'
execute 'sysupgrade -F /bin/busybox'
Download the Asus Firmware Restoration tool (I used version 2.1.0.3): Tool download link