Have you set server: true in config :your_app, YourApp.Web.Endpoint?
Also, here’s a pretty good guide on using phoenix with nginx (and let’s encrypt) Using LetsEncrypt with Phoenix (behind Nginx). How to make this more optimal?
You might also want to read through some distillery (which edeliver uses underneath) guides on hexdocs https://hexdocs.pm/distillery/getting-started.html, especially the phoenix parts.
