Is it possible at all to run websocket based godot server from standard webservers like IIS, Apache
IIS seems to integrate this ... comes up as first google search result
Apache usualy not
When exported in HTML5 (GLES3) and deployed to IIS it seems the WebSocketServer part is having difficulties establishing listening port (8000): Error listening on port 8000.
You need a websocket server running on the port or else you cant connect. The browser cant establish a socket, it only can connect to one.
If exported to Windows executable the chat Server works (is listening). Interesting is that we can disable support for WebSocket on IIS and chat Clients in web browser have no problem connecting to standalone server (Windows build) that uses websockets.
The IIS doesnt hinder the browser from connecting to the executables socket.
I think your understanding of WebSockets workings isnt to good. Maybe you want to google for some tutorials that clearifies the subject.