Probably depends on which driver is being used. For the indi_ioptronv3_telescope driver used by GEM28 and GEM45, the default baud rate is 115200
iOptronV3.DEVICE_BAUD_RATE.115200=On
Which driver does the AZ MOUNT PRO use? If it's the IEQ the default is 9600
iEQ.DEVICE_BAUD_RATE.9600=On