Domoticz

I have done a new installion of Domoticz on my Rapsberry PI v3. I installed Domoticz under (?) Docker. Looks OK. Buienradar nl works perfectly, but when I try to install in "hardware" my P1 smart meter, I cannot define the Serial Port. Pull Down menu is empty. I have tried everything I could find online.
I checked that input from the meter is entering the Raspberry OK.

If you use Docker you have to map your RPi serial device to a docker serial device in the docker compose file.
See section serial port on the wiki page about the docker install. https://wiki.domoticz.com/Docker#Serial_Port