Firmware files starting from build 1283 are named openwrt-r.... Firware files before build 1283 were named lede-rt.... There is a special procedure described later to downgrade firware from openwrt to lede due to board detection change in the OpenWrt project.
Nand flash has different partitions (ubi volumes) for stock and
lede firmwares. This makes flashing more sophisticated for Asus
RT-AC58U compared with other routers.
More information and more details can be found on 4pda
(1) Download two firmware files from http://lede-ac58u.zyxmon.org/firmware/:
openwrt-r...-factory.trx (step 1 firmware) and
openwrt-r...-sysupgrade.tar (step 2 firmware). Flash openwrt-r...factory.trx
via web browser in a standard way. Now the firmware will appear to work and will work,
however any settings will be lost on reboot. To fix it you need to flash second step firmware.
(2) Login to router using SSH (ip 192.168.1.1, user root, no password) and delete ubi volume named jffs2. First check if jffs2 is not mounted, because it will prevent volume deletion. Run mount command, if the output has /dev/ubi0_5 on /mnt/ubi0_5... substring unmount partition with umount /mnt/ubi0_5. If the volume is not mounted it still might exist. Delete volume jffs2 with ubirmvol /dev/ubi0 -N jffs2. Verify that volume was deleted by running ubinfo -a. You should not see jffs2 in the output.
(3) Use your web browser to flash second step firmware. Router ip is 192.168.1.1, user root, no password. Update firmware - install openwrt-r...-sysupgrade.tar as a new firmware. After router reboots you will have the latest lede firmware on it. If you get an error The uploaded image file does not contain a supported format. Make sure that you choose the generic image format for your platform might be that you have not deleted jffs2 volume correctly. Try deleting again.
Check firmware URL and upgrade firmware on a regular basis.
(first "automatic" firmware was build by dullish 4pda.ru
forum). This firmware has sysupgrade.tar file inside it and runs
operations from Method 1 automatically. Please note that
stock2lede does not install the latest lede firmware. Total time
to flash sock2lede is about 6-10 minutes. Use your web browser to
flash the latest firmware after flashing stock2lede.
This method requires router disassembly and some skills. You will
need (usb-uart) for it and *.itb firware. More
details (Russian) are here - 4pda.
Firmware downgrade from build 1283 and later to build previous to 1283 (To downgrade openwrt... to lede...) can be done only in ssh session. 1. Rename the firmware file lede.....sysupgrade.tar to lede.tar (make filename shorter). 2. Upload it to /tmp router folder. 3. Run sysupgrade -F /tmp/lede.tar. Flag -F (force) overrides the image format check that was changed in the OpenWrt project. Here is an example (firmware downoad + rename + upgrade:
root@LEDE:~# wget http://lede-ac58u.zyxmon.org/archive/lede-rt-ac58u-r1057-ed83357-ipq806x-RT-AC58U-squashfs-sysupgrade.tar -O /tmp/lede.tar Connecting to lede-ac58u.zyxmon.org (184.108.40.206:80) lede.tar 100% |*****************************************************************| 6680k 0:00:00 ETA root@LEDE:~# syspgrade -F /tmp/lede.tar
(1) The latest firmware has additional repository (installed
automatically) with kernel kmod packages.
If you need kmod packages use the latest firmware from this site.
(2) usb-uart method allows to restore router from nearly all firmware flashing errors.
To go back to factory firmware you need to remove ubi volumes that are different in lede and stock. After router reboots U-Boot bootloader will automatically restore stock partitions and enter recovery mode. To delete ubi volumes we will use sysupgrade script with -F (force) flag and junk firmware. In this case sysupgrade will remove three volumes linux, rootfs and rootfs_data. Since we use junk file as a firmware sysupgrade will not be able to calculet new volumes sizes and will reboot router. To avoid bootloop we will remove linux2 volume wich is a copy of linux volume. Login to you router using SSH and run (1) ubirmvol /dev/ubi0 -N linux2 (we delete linux2 volume) and (2) sysupgrade -F /bin/busybox (we use busybox as a junk firmware). After the router reboots use Asus Recue utility (Windows) or tftp client binary to send RT-AC58U.trx stock firmware.
I just purchased ASUS RT-AC58U and decided to follow Method 2 (automatic) of How to flash LEDE firmware. It seemingly succeeded, but I got stuck with Lede and The uploaded image file does not contain a supported format error. The partition in question did not exist, so I decided to do sysupgrade -F. After it, the router entered a boot loop.
Hopefully, I was able to flash stock2lede.trx again via tftp, and then I found a reason of my failure:
Automatic method did not fully finish the step (3). Second time, I decided to flash openwrt-r1834-0f04829-ipq806x-asus_rt-ac58u-squashfs-sysupgrade.tar via web. And voila, it worked, and after the reboot I was able to flash the latest OpenWRT.
So here are two updates to your manual:
1) If you get The uploaded image file does not contain a supported format error message, and jffs2 does not exist, try to step (3) from Method 1 manually. Step 2 was probably not automatically finished.
2) If you get a boot loop due to missing jffs2 partition, try to upload stock2lede.trx instead of stock firmware via TFTP. You may fix your boot loop without opening the device.