WebRTC not working without internet connection

Good morning,
yesterday I installed the last FreeBPX distro on my Raspberry and configured everything to work with WebRTC. I have two problems:

  1. If the Raspberry is connected to Internet, WebRTC call from UCP panel works fine (the phone icon is green and browsers can connect to websocket server on the Raspberry). If the Raspberry is not connected to Internet, WebRTC call from UCP doesn’t work (browsers can’t connect to websocket server and the phone icon is yellow). In both cases the raspberry has a fixed IP address. Is there something I can check in the configuration?

  2. When raspberry is connected to Internet, the only webrtc calls that work are those made directly from UCP panel. All others attempts (sipML, SipJS, JSsjp and so on) don’t work. I need to embed webrtc call inside my existing website. Is there a working example not linked to the UCP?

Hope someone can help me!