@mfalkvidd Yesterday I stopped trying and shutdown the Pi. This morning I tried the same again and it works !!
Pretty sure I haven't done anything else.
Thanks anyway.

Sander

Wow ! speed of light ;-)
Thanks. All clear.

@GertSanders Thanks Gert !
I did a quick build of the serial gateway using an arduino which I connect to my RPI. Pretty easy. I'll be watching this when I can switch back to the RPI built gateway...