I got similar problems.
1. If I use iPhone safari 11.3 to connect the easyrtc demo-audio example, nothing can be heard but the other side can hear what I say. I guess the reason is Safari not yet support easyrtc or other webrtc.
2. Sometimes the peer to peer connection cannot be established. Again I guess we need to install our own TURN server in order to increase the chance of successful connection, as the server-demo example is only equipped with STUN servers, but not TURN servers.
Pls. let me know if I'm wrong, thank you.