192.168.0.15 is your local IP address.
Only your computer and others on your network can use that number (or Locahost for your computer only)
http://whatismyipaddress.com will give your Internet IP Address
Your router has to be told what address on your local network (FMP IWP hosting computer) to forward requests to from outside your local network
The question has been answered many times here. https://www.google.com/search?q=iwp+portforward+site%3Aforums.filemaker.com