Two Bluno/ BLE devices cannot communicate properly?

Common suggestions for communication problem:

1. Update the firmware to the latest version;

2. Apply the default setting by AT command AT+SETTING=DEFAULT;

3. Check if the serial port is used correctly if you use Leonardo, Mega etc which contains multiple serial ports. e.g. Leonardo uses Serial1.****() instead of Serial.****() for the I/O Pin 0,1. The Serial.****()is for the USB port.

Check if the baud rate in different places are corresponding: （38400 is suggested for 8MHz boards）

4. In codes > Serial*.begin(?)

BLE modules > Baud rate setting

5. Reboot the module.