@mg10: You probably failed your password switch, or missed something (hint: read the doc).
Switch SSH over WiFi off in KUAL, cycle USBNet status to relaunch the SSHD, and do it properly this time
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Nope, over WiFi, IP handling is obviously done by your router. You'll still be able to connect over USB w/ the IP setup from usbnet/config, but you'll need a valid auth method (until ssh over wifi is disabled, and usbnet state cycled) over there too.
The 'swiss cheese' passwordless login is only enabled with: dropbear as the sshd, ssh over wifi disabled (i.e., the default settings). Any other combo requires a valid auth method, and since FW 5.3, the root account is locked, so there's no 'default' password.
And I reiterate that you don't need to reset to factory defaults, you can toggle USBNet from the searchbar no matter your settings. (read the docs).
In case you missed the general idea: read the docs.