Using local Flask API with Ionic app

I have a local Flask API at http://0.0.0.0:8000/, when I hit it from my ionic app that is loaded to http://localhost:8100/ via ionic serve everything works fine, but when I run the app from my iPhone via ionic build ios, the app no longer hits the API. Is there a way to make this work? I thought since they were on the same wifi network it would work fine.