I had Heishamon reporting to HA via Mosquitto v6.0.1 working with core v2021-11-5. After upgrading to v2021-12-5 (and supervisor to v2021-12-2) the dashboard stopped updating. Restarted everything, reinstalled Mosquitto (which cleared the stored values so they now show as Unknown), checked the logs (nothing obvious). Mosquitto is relaying its state and the HA status to an external client. If I point Heishamon at another broker, I see the Panasonic topics coming through. When using Mosquitto, it logs in using an HA user name/password, with certificates disabled. Any suggestions for further investigations would be welcome.
Now resolved - the firewall was blocking the MQTT messages from passing between local networks. (Change on behaviour at last firewall update?)