Google has deprecated Google Cloud Messaging. This version moves to Firebase Messaging and fixes a few issues caused by other recent Google API changes.
Previous versions of LANNouncer will stop working soon, probably around end-of-May 2019, when Google shuts down GCM. Consequently, this is a mandatory update.
If you have Premium, ensure "Enable GCM" (still called that) is on, rather than "No IFTTT Support", or the additional slots will not display.