Yaesu System Fusion reflector compatible with the YSFReflector/MMDVM IP protocol. Each accepted YSFD datagram (155 bytes) is relayed unchanged to every other linked gateway. The payload is native: V/D, voice-wide and data frames are not decoded, transcoded or enhanced.
Point YSFGateway, Pi-Star, Nexus-BS or another YSF client at UDP port 42000 with your callsign. The gateway polls (YSFP) every few seconds; the reflector answers with a 14-byte poll. A link expires after 60 seconds without a poll. YSFU unlinks immediately. YSFS returns the 42-byte reflector status used by registries.
YSF has no talkgroups: this is a single room. The first gateway to send data owns the room until its end-of-transmission bit or 1.5 seconds of silence; frames from other gateways meanwhile are dropped and counted as busy. Continuous transmission is limited to three minutes by default, followed by a short cooldown. DG-ID rooms and Wires-X commands are not supported.
IP and callsign allowlists, blocklists, per-IP rate limits and bounded capacity are set in config.toml. Empty allowlists permit public reflector access. The legacy UDP protocol does not authenticate identity cryptographically. The public dashboard is read-only. The administrative stop-stream operation requires a bearer token and is bound to loopback.
Recent transmissions and counters survive a clean restart. Atomic, synchronized state snapshots occur every five seconds; an abrupt power loss may lose that interval. Health reports missing telemetry, resource pressure, persistence and network errors. Metrics are available at /status/metrics.