Ok so I made a new gateway with an Arduino Nano and do not have any error anymore but I can not add any devices.
I contacted the people from Vera because my serial port option is gone.
They were able to reactive it but they told me "Arduino seems to be a replica (it should use FTDI) " which probably mean I have to order new one. Are you aware of this issue ? is this a show stopper as they seem to imply.
I will probably order what I need now and in the mean time I thank you all for your help.