I love this project. It's gapless playback is perfect and exactly what I need, although I prefer the web interface for controlling plexamp.
So when I'm on the home network, I have no problem casting to the local plexamp. I can see the app available to cast to, and I have full control. However, outside of my home network, the web interface (running directly from my fileserver) cannot see any versions of plexamp to cast to. However, under status > now playing, it can see that plexamp is playing, so it knows it exists and is working, but it appears the remote control only works one way.
Is there some particular settings I need to adjust in the json config files (or plex server itself), or can plexamp simply not be controlled remotely from a web interface when it's not inside the local network?