Wio Lite W600 serial port stuck at 9600

Hi, I’m experimenting with a Wio Lite W600 but I faced a problem with the serial communication. At first power-on the module works at 9600 baud, as in the demo projects, but the command “AT+UART=?” responds 115200. Changing the baud rate with, for example, “AT+UART=!57600,0,0,0,0” causes the new rate to be correctly recognized by “AT+UART=?” but the module still works at 9600. Please, is there the need of a special sequence of commands to set the new baud rate? Thank you.