@gertjan Thank you very much. The Host Override done the job. I also find that I might have wrong DNS resolver settings: I choose both the "Network Interfaces" and "Outgoing Network Interfaces" to all.
However, I do not understand why I cannot use Scenario 3 to access the website. The "Host override" option in DNS resolver override the IP address of the public IP to the webserver local IP, making it to Scenario 2.