This is my issue. I have Stunnel running on a Windows Virtual PC using port 8443, My firewall is doing port mapping and everything works, meaning the WAN port sees 8443 open using Open Port Check tool. When I loaded Stunnel on my Raspberry Pi, changed the port mapping to point to the Pi, Open Port Check tool can't find port 8443.
In doing some searches on the Internet, it seems that the Pi has no firewall on it.. I'm also new to Raspian, Linux, etc and I read about iptables but I don't get it (if this is my issue).
Any help would be appreciated.