webrtcbin: connection is not established without remote candidates (even when they are not needed)
add-ice-candidate is not called, connection will not be established.
However, if running with public IP address (on a server) it is not needed.
As a proof, this nonsense is sufficient to trick GStreamer into not requiring real proper candidates and establish connection successfully:
webrtcbin .emit( "add-ice-candidate", &[&0u32, &"candidate:0 1 udp 0 0.0.0.0 0 typ host".to_string()] ) .unwrap();
Would be nice to remove the need for such a hack entirely.