i have a Raspberry Pi with Node Red, nothing else till now.
i have a second Raspberry Pi with a 433 Dongel and installed like this
to collect and view it on the Monitor works!
then installed mosquitto-clients
sudo apt install -y mosquitto-clients
and done this command
rtl_433 -F json -M utc | mosquitto_pub -t home/rtl_433 -l
i found out the Port 1883 is closed on the this device. but found no config file
and yes sorry basicly it is not a Node Red Proble
but the next step will be the connection
have a nice day