That did not work for an AR300M trying to get OpenWrt 21.02.0 NAND firmware to load with uboot, as the new uboot loader seems to look at the file extension of .bin and decides it is a NOR code load. Renaming the OpenWrt NAND .bin file to .img, and using uboot just bricked the router, so I ended up loading the NOR OpenWrt .bin firmware with uboot, then power cycled it enough times to get it to boot the NOR firmware, and finally used sysupgrade while running the 21.02.0 NOR firmware to load the NAND 21.02.0 OpenWrt firmware. Great way to blow off a day. It never is as straight forward as it should be and is different with everyone of your router types.