Hi Apple Support team,
Just to be clear, this is a User-to-User forum. It is not a channel to Apple Support. But often you can get very good help here.
The obvious question is, do you have System Preferences -> Sharing -> Remote Login enabled?
Does your /etc/hosts file have a correct 'localhost' entry
grep localhost /etc/hosts
# localhost is used to configure the loopback interface
127.0.0.1 localhost
::1 localhost
fe80::1%lo0 localhost
Does your ifconfig lo0 look something like this:
ifconfig lo0
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
options=3<RXCSUM,TXCSUM>
inet6 ::1 prefixlen 128
inet 127.0.0.1 netmask 0xff000000
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1
nd6 options=1<PERFORMNUD>
Are you running any 3rd party utilities that might be monitoring your network communications, such as an anti-virus package, or LittleSnitch?
Are you running any VPN software, and is it actively connected to the remote VPN server? Some VPN setups block ALL from connections across the VPN.