hello matteoluci81,
there’re 3 UARTs available for Jetson Xavier NX, UART0 to M2; UART1 to 40-PIN; UART2 to debug.
here’re some similar discussion thread for your reference,
please check Topic 160948 for the steps to disable combined uart on Xavier series,
it’s Topic 170116 to talk about use it as normal uart serial port.
thanks