Hello, did you find the answer to this question? I have exactly the same issue when I am trying to use SET with the my public IP. My ISP is blocking inbound traffic on port 80, so I tried using port 443 and 8080 and in the same way I am able to open my webpage from outside IP addresses, but when I enter test credentials and hit sign in - the page keeps loading and SET does not capture anything. I went one step further, and configured to get HTTP request traffic on myPublicIPaddress:443 and then forward it to myPrivateIPaddress:80 , and in the same way when I try to test from my cellphone connection, I can open the webpage, but I can not capture the credentials (I am using Credential Harvester > Web Templates > Google)
Please let me know if you found a solution or an alternative method to that can be used with the public IP addresses