If the stream freezes mid-stream (e.g., 15 or 30 minutes) in, that seems to be an issue quite a few people have had when on bad connections. New code has been added in hopes it will reduce how often that happens, but just refresh if this happens. OBS.Ninja should auto-refresh frozen streams on its own in most cases after a few second.
iOS users can only send video to 3 viewers at a time. After that, videos will start freezing or turning black.