DFL cannot to replace website contents by FQDN (DNS name), but you can try to do it on IP address base...
1) Find all server IP addresses (ex, by network-tools.com)
In your case, it's 74.208.43.192
2) Make rules before lan_to_wan1 folder
SAT lan/lannet wan1/74.208.43.192 http-all (SAT: new destination = 1.2.3.2)
NAT lan/lannet wan1/74.208.43.192 http-all