You don't need to do all of that.
Just pair your AstroBox with your cloud account and you'll be able to monitor your printer from anywhere.
*In order to do this, click on the ROCKET ICON on the top right corner of your AstroBox Settings.
The entire point of Astroprint (and the AstroBox) is to PREVENT you from mucking around with technical stuff like ddns/port forwarding etc..
Let me know if that makes sense