digraph G {
    node [ shape=box ]
    rankdir=LR;

    client1 [ label="IPv4 client 1\nPrivate IP" ];
    client2 [ label="IPv4 client 2\nPrivate IP" ];

    nat_gw  [ label="NAT gateway\nPublic IP"  ];
    cgnat1  [ label="CGNAT gateway\nPrivate IP"  ];
    cgnat2  [ label="CGNAT gateway\nPublic IP"  ];
    target  [ label="The Internet\nPublic IP" ];


    client1->nat_gw->target;
    client2->cgnat1->cgnat2->target;
}