The MOST common causes are:
Cause 1: TC417 did not enter PAIRING MODE.
Solution: Enter TC417 into pairing mode - Press and hold PAIR button for 2 seconds to enter into pairing mode, the LED indicator will flash GREEN(TX) rapidly.
Cause 2: Your Bluetooth headphone/speaker did not enter PAIRING MODE.
Solution: Enter your Bluetooth headphone/speaker into pairing mode - please refer to relevant user manual, usually LED on Bluetooth headphone flashes RED and BLUE alternately or flashes BLUE quickly).
Cause 3: Your Bluetooth headphone/speaker or TC417 is connected to other unwanted Bluetooth device.
Cause 4: Affected by around wireless devices, e.g. wifi router.
Solution for Cause 3 & 4：Turn off all other around Bluetooth devices and keep the TC417 away from wifi router, then follow below steps to pair the TC417 and your Bluetooth headphone/speaker again:
Step 2: Reset/clear paired history of your Bluetooth headphone/speaker - refer to its user manual.
Step 3：Enter your Bluetooth headphone/speaker into PAIRING MODE - refer to its user manual, usually LED on Bluetooth headphone flashes RED and BLUE alternately or flashes BLUEquickly.
Step 4: Keep them close and wait for connect. Once connected, LED on TC417 turn SOLID GREEN.