Checking refusal of a network connection

[Markus Elfring]

>> I would expect that the IPv4 address from such a connection attempt
>> would be automatically converted to a IPv6 loopback address.
>
> You haven't said which OS you are using, but as far as I know this
> expectation will be frustrated at least on Linux: There ::1 and
> 127.0.0.1 are distinct addresses.

How does this view fit to information from the Linux programmer's manual?
See also: command “man 7 ipv6”

Regards,
Markus