If that could make you feel better, I tried in the past to create a trial web app, I opened the ports in firewall, I was able to see the webapp in my pc from my mobile phone connected in the same wifi but I wasn't able to see it with port forwarding from my router and an "outside" visit. Until now I was not able to find out what's wrong. I have an IIS installed too.
Edit - please note that the webapp jar is by itself a server and it shouldn't be placed in an IIS folder for working. It just opens and accepts connections.