Build Build a video calling system with webRTC and flask.

I need a simple HTML file from where the user can make a video call. Do not think about the design and other things. Just build the core component of a video calling app. I already tried to make my own, but I'm facing some technical difficulties. Right now, my system supports 1 to 1 video calls and it works in the same network. You have to configure a TURN server and make a video calling system for multiple users. It should work over the internet. You can make your own app or modify my app.
my 2 problems:
1. my TURN server is not working.
2. my app doesn't support video calls for multiple users

I don't care about how you solve the problem. Fix my app or make your own. just do it.