How to make a receiver on Android phone like AirReceiver or CastReceiver?

Question

 [  0.000s] [cast.receiver.IpcChannel] Opening net websocket 
cast_receiver_framework.js:742 Lit is in dev mode. Not recommended for production! See https://lit.dev/msg/dev-mode for more information.
ao @ cast_receiver_framework.js:742
cast_receiver_framework.js:837 CAST SDK CAF Version: 3.0.0105
cast_receiver_framework.js:121  [  0.238s] [goog.net.WebSocket] Opening the WebSocket on ws://localhost:8008/v2/ipc 
media_player.js:120 CAST SDK MPL Version: 1.0.0.114
cast_receiver_framework.js:577 WebSocket connection to 'ws://localhost:8008/v2/ipc' failed: 
_.h.open @ cast_receiver_framework.js:577
cast_receiver_framework.js:121  [  2.575s] [goog.net.WebSocket] An error occurred: undefined 
vh @ cast_receiver_framework.js:121
cast_receiver_framework.js:121  [  2.577s] [goog.net.WebSocket] The WebSocket on ws://localhost:8008/v2/ipc closed. 
cast_receiver_framework.js:121  [  2.578s] [goog.net.WebSocket] The WebSocket disconnected unexpectedly: undefined 

I don't know why WebSocket connection to 'ws://localhost:8008/v2/ipc' failed. I thank you in advance. please help me.

I want to make a receiver on Android phone like Air Receiver or Cast Receiver. So, I make the code following google test code.

In addition, a firebase host server supporting https was built.

Load HttpsUrlConnection the server (firebase host server) when app is launched. However, the following error occurs and other Android or iPhone devices cannot find the cast receiver device I created.