Thank you very much for your help, now I succesfully connected my iboard card as LAN Gateway without doing any HW modification and even any software modification to any library, simply using the sketch you sent here.
For general information to other people that want to use the iboard card with Domoticz, to avoid any problem like the following:
2016-12-18 12:06:40.840 MySensors: trying to connect to: 192.168.1.133:5603
2016-12-18 12:06:41.841 MySensors: connected to: 192.168.1.133:5603
2016-12-18 12:06:45.841 MySensors: Connection reset!
2016-12-18 12:06:45.842 TCP: Reconnecting in 30 seconds...
Consider to use the Arduino IDE 1.6.8 to compile and upload the sketch, otherwise, with newest Arduino IDE you will get the error messages above.
Thank you again for you help and a big hello to all the members of the forum.