The overlay of the router is expanded by the method of the above document. If the USB used by the Kurong overlay is disconnected or damaged, can the device start normally? If it can’t start normally, how to restore it? If it can start normally, does the overlay return to the state before the extension?
OpenWrt falls back to the original overlay if it fails to mount extroot at startup.
It's typically labeled as rootfs_data and should be mounted to /rwm if you follow the wiki.