I run Emby in a docker container behind a public-facing reverse proxy (& a separate internal reverse proxy, but I don't think that's relevant to this issue). I can access the server normally in web browsers on my LAN with or without the reverse proxy. I can also access it externally through the reverse proxy. However, the Emby Roku app on my TV (on LAN) cannot connect, throwing error "500: The requested URL returned error: 500 Internal Server Error" attempting to connect either through rever