I recently purchased Avantree DG40S Wireless 4.0 Micro USB Adapter for my Toshiba Satellite A505 laptop. It would NOT work. I sent Avantree support the following e-mail:

Support,

I received from Amazon the Avantree DG40S Wireless 4.0 Micro USB Adapter.
Delivered Wednesday, May 16, 2018
My laptop is Toshiba Satellite A505-SG025.
Operating system: Windows 10.
Audio Bluetooth Headsets are Apple AirPods.

Problem is the Apple AirPod headsets will not stay paired. I hear no audio.
What I have done:

• Updated all of Windows 10.
• Updated all the Bluetooth devices.
• I have tried to pair my headsets to your DG406 Bluetooth USB numerous times.
• I have tried inserting your DG406 Bluetooth USB into all 4 USB ports on the laptop and have rebooted Windows after each port change, trying to get the device to operate properly.
• I have tried to get “choose your output device” to show anything other than speakers. No success.
• I have performed “Troubleshoot” when available. I get a message that the headsets are not connected.
• The Bluetooth device flashes continously a LED light when inserted in my laptop USB ports.
• Your DG406 appears as a Bluetooth device (CSR8510 A10) and will pair with the headsets but will NOT stay connected. My headsets only connect for a second or two and then disconnect.

Solution:
I am not exactly sure what made the headsets work so let me go through some of my last efforts:
I kept finding that I had Realtek audio in my laptop. I searched and found their Windows 10 drivers and installed them. I then tried to pair my headsets but now I found that the USB port at the rear left did not allow the Bluetooth device to flash it’s LED.

I selected Troubleshoot and Headphones – AirPods No jack information available. I had done this numerous times but now I ran this task with the Bluetooth device plugged into the left front USB port. The results of the test shows a list of audio possibilities that the computer will then start testing. I believe I chose the AirPods and this time something new took place. I noticed that pop up windows appeared that indicated that Windows was installing new software to recognize the AirPods. Then the computer window for Sound that shows “Choose your output device” now showed Headphones (AirPods Stereo). The Windows screen for “Bluetooth & other devices” showed the Audio list of devices as “AirPods Connected voice, music”. That was new.  Previously it only would show AirPods Paired.  The computer screen never before showed “Connected”.  I took one of the AirPods out of its holder and there was my test audio running. I finally got it to work after 3 days of trying everything. What a royal pain!

PS: I purchased this Bluetooth because my very old D-Link DBT-120 would cut out at about 8 to 10 feet from the laptop.    The old device worked perfectly with my new AirPods with absolutely no difficulty except I was getting tired of having to pull the AirPods out of my ear when I went to the kitchen to get some food or tea..  The new device worked for about 20 feet so I could now keep listening to my music while in the kitchen.