iSub app won't connect

[Tomo]

I've got Subsonic running on my Macbook Pro (OSX 10.8.5), and port forwarding on [my account].subsonic.org is set to automatic, and it's status is successfully forwarding to port 4040. iSub on my iPhone, however, can't connect unless I'm on the same Wifi network as my Mac.

Subsonic/iSub has been working for my for years. I recently installed v5.0, thinking maybe that would improve something (i.e. it wasn't broken, but I tried to fix it), and it suddenly stopped working. I went back to 4.8, which was the last version I'd had, and while I can still login on my Mac, I can't connect outside of my own network.

Any advice as to how to fix this?