Sufficient Flash to accommodate OpenWrt/LEDE firmware image
4MB min (won't be able to install GUI (LuCI))
8MB better (will fit GUI and some other applications)
Sufficient RAM for stable operation
32MB min, 64MB better
Devices with ≤4MB flash and/or ≤32MB ram suffer from limitations in usability, extensibility and stability of operation. Consider this when chosing a device to buy, or when deciding to flash OpenWrt on your device because it is listed as supported. See 432_warning for details.