A read-only status string reporting the health of the Contivity's multicast relay feature, which forwards multicast traffic across the gateway. Applications relying on multicast, such as some video or discovery protocols, will silently stop working if this relay isn't Healthy, so an admin uses this object to rule out the gateway when troubleshooting multicast delivery problems. If users report failing multicast video streams through the VPN and mcastRelayStatus shows "Alert," the admin can point to the relay itself rather than the application as the cause.