Sometimes, you need TURN server to setup between audio or video session between wifi and 4G. Using only STUN server may not work. Please check
if you have setup and configured STUN and TURN server properly.
>>The information on the exchanges goes well and I feel the presence of the videos on the page but it is not displayed
For efficiency, signaling and media doesn't take the same path. In your case signaling is working fine but not the media session.
You can check in the "chrome://webrtc-internals/" if the ICE check has been completed or not.
Thanks,
Shakeeb