sterretje:
USB needs a host; you can recognise hosts by the A-type connector (like on a PC). You can connect multiple 'slaves' (mouse, keyboard, Arduino etc) to a host. You can not connect slaves to slaves and you can not connect hosts to hosts and get a working setup.
Right. Makes sense now. Is it possible to set one Nano as master and leave the other one as it is (slave) and use the micro-usb ? (no i2c)
I've just started researching this. Thank you!