I have found the preboot script.
issue is with the sequence rt2800usb, rt2x00lib, rt2800lib
start-wifi script get as MODULE this sequence rt2800usb, rt2x00lib, rt2800lib that make fail modprobe -r (modprobe is expecting only one module) then modprobe rt2800usb, rt2x00lib, rt2800lib fails for same reason. I have modified the MODULE variable to get sequence rt2800usb rt2x00lib rt2800lib and then modprobe -r now works. I got to replace modprobe by modprobe -a to get
modprobe -a rt2800usb, rt2x00lib, rt2800lib working. Unfortunately it fails a bit later. As I’m not a unix expert I don’t understand anything to the script.
I can’t go further 😥