@Westie Testing using a docker image of the gateway... Update looking good - I have dropped the baud rate down to something more compatible with my clone nano.
I found a useful tool to check the incoming serial from a Python point of view (not running the adapter when I do it) - python3 -m serial.tools.miniterm --parity N /dev/ttyUSB0 19200. This prints out the messages from the Serial Gateway in nice text when the speed is correct.