Hi all. I have followed your advice(s) and got rtl_433 running on HA via the Add-on. And it is picking up the rain gauge in the garden - all good. I did also install the partner add-on rtl_433 MQTT Auto Discovery and configured it to talk to my MQTT server and that works too - log file no errors and connected to MQTT server.
However the rtl_233 add-on does not seem to be passing the discovered rain meter reading to rtl_433 MQTT Auto Discovery and then on to HA MQTT. The rtl_433 MQTT Auto Discovery log just shows connection info on MQTT but no sent data to it. And looking at the MQTT integration there are no new devices or entities.
Does anyone know what i may have missed on the config? I am so close!! Thanks for any help you can give me.