The RTCPeerConnectionIceErrorEvent property address is a string which indicates the local IP address being used to communicate with the STUN or TURN server during negotiations. The error which occurred involved this address.

A string which specifies the local IP address of the network connection to the ICE server with which negotiations were occurring when the error occurred. This address identifies the network interface on the local device which is being used to attempt to establish the connection to the remote peer.

This can be useful on multi-homed systems—devices with more than one network connection—to determine which network interface is being used. For example, on a mobile phone, there are typically at least two network interfaces available: the cellular connection and a Wi-Fi connection.

If the local IP address isn't exposed as part of a local candidate, the value of address is null.

This example creates a handler for icecandidateerror events which creates human-readable messages describing the local network interface for the connection as well as the ICE server that was being used to try to open the connection, then calls a function to display those as well as the event's errorText property's contents.

pc.addEventListener("icecandidateerror", (event) => {
  let networkInfo = `[Local interface: ${event.address}:${event.port}`;
  let iceServerInfo = `[ICE server: ${event.url}`;

  showMessage(errorText, iceServerInfo, networkInfo);
});