About a couple of months ago, I went from OpenWRT to Gargoyle on my Netgear R6220 router. You can read more about it here. I had setup a couple of networks with one hidden and not isolating clients whereas the other one doing the reverse. Now everything was OK but the Gargoyle used to crash my kernel whenever a new device tried to join the unadvertised network. The different interfaces were also brought down. Again, there are certain features of OpenWRT that I really missed with one being the ability to create multiple virtual radio interfaces and the other being the flexibility with adblock host lists.

So, I wanted to go back to OpenWRT. Gargoyle runs on top of OpenWRT but both the kernel and the rootfs were modified to a very big extent by Gargoyle. Telent was not enabled and doing a sysupgrade didn’t work for me. So I did the following procedure to get back to OpenWRT from Gargoyle.

root@Andromeda:~# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00100000 00020000 "u-boot"
mtd1: 00100000 00020000 "SC PID"
mtd2: 00400000 00020000 "kernel"
mtd3: 01c00000 00020000 "ubi"
mtd4: 00100000 00020000 "factory"
mtd5: 03c00000 00020000 "reserved"

As can be seen above there are 6 mtd devices on the R6220. MTD2 (kernel) and MTD3 (ubi) are the kernel and the rootfs respectively. Since sysupgrade was throwing invalid file format errors, I had to do mtd writes on the respective MTD devices directly using the command below.

mtd -r write /tmp/kernel.bin kernel
mtd -r write /tmp/rootfs.bin ubi

The above allowed me to go back to OpenWRT without the LUCI interface.

opkg update
opkg install luci

Allowed me to install Luci and configure my router like normal. In the middle, I did need to do a

sysupgrade -n -v /tmp/sysupgrade.bin

to get to a nice working OpenWRT version. The packages for the router are available on “OpenWRT Snapshots”. Hope this helps!