Running TTN back-end locally reports gateway errors

It might just be node-red that is not able to do so, or that I have not the right docker-compose file? My only change that I have made to TTN basic docker-compose file is the below one besides having enabled the No public access to the downlink RPC port (on broker & router) and* No public access to the uplink RPC port* (on broker)

  node-red:
        build: $HOME/TTNbackend/build/node-red
        volumes:
          - /var/lib/docker/node-red/:/root/.node-red/
        links:
          - mosquitto
          - broker
        ports:
          - "1880:1880"

If yo make use of ttnctl to instruct a donwlink packet, could you tell me the command that ttnctl does (I mean the implementation not the high level command)? Maybe I may work from that point with node-red, or asking them about that

Thank you very much for your help @htdvisser