More about this here
I have downgraded/upgraded my router countless times when testing different things and I wonder why...
Why the hell do you have all this unplug, reset, unplug, etc. in your downgrade instructions?
Why do you even have to load 1.21 firmware?
All I have ever done is load the RU firmware, let router reboot then load the 1.11 firmware without any resets, unplugging.