Trouble using rs485 and Modbus on reComputer R1000

Hi, I have received v1.0 of R1000 but impossible to get working RS485 on any port.
I followed the kernel mode but without success. It works great on v1.1 by the way.
I didn’t flash a new OS but tried with the one that comes shipped. I followed the instructions and tried on two different devices and I see that it hooks up correctly in dmesg but no success communicating with another device.