Https://appr.tc Is Down. How To Set Up Own Signaling Server/ Room Server URL?

I'd developed a video calling app on Android using WebRTC and was using the https://appr.tc as the signaling server (Room Server URL). But according to https://groups.google.com/g/discuss-webrtc/c/H7XuZfgkGH0 apprtc is now taken down. When I run the AppRTC demo app I get the following error:

Connection Error
Non-200 response to POST to URL: https://appr.tc/join/room_id32864 : HTTP/1.1 404 Not Found

Could someone please show the way on how to change the Room Server URL or setup my own Room Server URL? Any help would be appreciated. Thanks

The source code of apprtc remains available on github: https://github.com/webrtc/apprtc

You might want to read this blog post about whether to use it though: https://bloggeek.me/webrtc-signaling-server-not-use-apprtc/ The project has been effectively abandoned for years and you will have a hard time finding support.