I am trying to connect WebRTC video and audio in iOS connected by 3g/4g gives error but works fine with WiFi network.
And after the peer connection is found the error appears
[carc] CAReportingClient.mm:320:-[CAReportingClient sendMessage:category:type:reporters:]_block_invoke: The operation couldn’t be completed. No valid RTCReporting and the session was started
Call setup failing on 3G/4G but working in a local network is symptomatic of a STUN failure. See if you are supplying at least one valid STUN server to the WebRTC engine in your iOS code.
Edit: It's also possible that a peer-to-peer connection cannot be established in your 3G/4G setup. So you also need to make sure you are supplying a valid TURN server as well.
来源：https://stackoverflow.com/questions/48057400/webrtc-video-and-audio-in-ios-not-working-with-3g-4g-but-works-with-wifi