WebRTC ICE Candidate Exchange Must Complete Before Media Flows

WebRTC connection established (RTCPeerConnection state shows 'connected') but no audio/video arrives. Media tracks added but never render on the remote side.

Ensure ICE candidates gathered by each peer are sent to the remote peer via your signaling channel and added with addIceCandidate() before the connection can carry media. Candidates arrive asynchronously after setLocalDescription(), so you must buffer and relay each one.

const pc = new RTCPeerConnection({ iceServers });

pc.onicecandidate = ({ candidate }) => {
  if (candidate) {
    signalingChannel.send({ type: 'ice-candidate', candidate });
  }
};

// On receiving a candidate from signaling:
signalingChannel.on('ice-candidate', async ({ candidate }) => {
  try {
    await pc.addIceCandidate(new RTCIceCandidate(candidate));
  } catch (err) {
    console.error('addIceCandidate failed', err);
  }
});

ICE (Interactive Connectivity Establishment) is a separate negotiation layer that discovers viable network paths (direct, STUN-reflected, TURN-relayed). Without exchanging candidates the browser has no route to send RTP packets through.