Why the Administrator Cannot Log In to the Device After the Authentication Mode in the Default Authentication Scheme Is Set to Non-authentication in a

In an anonymous login scenario, the AAA authentication mode needs to be set to nonauthentication.
If anonymous login users use the authentication scheme default, the authentication mode of
the authentication scheme default needs to be set to non-authentication.
By default, the authentication scheme default is bound to the domain default_admin. If the
administrator uses the default domain configuration and default authentication scheme, the
AAA authentication mode is non-authentication when the administrator logs in.
When the administrator logs in to the device using Telnet, the administrator is authenticated in
the VTY user interface by default and the default authentication mode is AAA (configured
using the authentication-mode (user interface view) command in the user interface view). If
the AAA authentication mode of the administrator is non-authentication, the administrator is
not allowed to log in to the device.