The baud rate is a hardware configuration option that can be changed when in manufacturing mode. Enter manufacturing mode using AT+CFUN=5.
The baud rate can be set using the AT+SQNHWCFG command. The complete current hardware configuration can be shown using AT+SQNHWCFG?.
In the following example, UART1 is configured at 921,600 bps in DCP mode:
AT+SQNHWCFG="uart1","enable","rtscts","921600","8","none","1","dcp"
Please refer to the Manufacturing Commands section of the AT Command Reference Manual for more details on this command.