Yes Max.Why you do not know server IP where stream is published? Do you have autoscaling group of Origins behind a load balancer?
You can use REST hook /publishStream, in this case you will always know Origin IP and stream published name on backend server.
You mean with custom backend server assigned to appKey.
If it is so, we need to have all API methods (like connect, publishStream, stopStream, StreamStatusEvent etc) allowed in the backend server.right?