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

    client1 [ label="IPv4 client 1\nPrivate IP" ];
    client2 [ label="IPv4 client 2\nPrivate IP" ];
    clientn [ label="IPv4 client n\nPrivate IP" ];
    nat_gw  [ label="NAT gateway\nPublic IP"  ];
    target  [ label="IPv4 Server\nPublic IP" ];
    nat_gw2 [ label="NAT gateway 2\nPublic IP"  ];
    client3 [ label="IPv4 client 3\nPrivate IP" ];
    client4 [ label="IPv4 client 4\nPrivate IP" ];
    clientx [ label="IPv4 client x\nPrivate IP" ];

    {client1, client2, clientn}->nat_gw;

    nat_gw->target;
    target->nat_gw;
    target->nat_gw2;
    nat_gw2->target;

    nat_gw2->{client3, client4, clientx} [ dir="back" ];


}