188.8.131.52 should work with either usb or Bluetooth.
Just had a mini test run. App version 1-38 with Sketch 184.108.40.206 and Bluetooth worked fine.
Things to check/confirm.
– Baud rate set to 9600
– correct value resistors
– resistors the right way around (the 1K resistor connects to the Arduino)
If all these look good try a serial pass through sketch and use a Android BT terminal app with the serial monitor to ensure you have the BT module communicating properly. See http://www.martyncurrey.com/arduino-and-hc-06-zs-040/. If you use the sketch there you will need to change the pins used. The example uses pins 2 and 3. Change these to 14 & 15.
Let me know how you get on.