The CD that came with the device listed RTL8671B, but it's not on Realtek's website. Instead the manual points you to:
https://www.mytechkey.com/pages/driver
4.Bluetooth 5.0 Dongle
Driver Link:
https://www.dropbox.com/s/gwo9lz777i82f70/BT5.0%20Driver.zip?dl=0
Hope that helps someone.
https://github.com/peteristhegreat/drivers-backup/releases/tag/1.0
Direct link
https://github.com/peteristhegreat/drivers-backup/releases/download/1.0/BT5.0.Driver.zip
Adding visibility to @carkrueger 's comment below
If you look here: https://www.catalog.update.microsoft.com/Search.aspx?q=realtek+bluetooth+1.6.1015 You will find now: 1.6.1015.3014 from 11.01.2021
Direct download link: http://download.windowsupdate.com/c/msdownload/update/driver/drvs/2021/02/0d13721d-7aa7-47cf-887a-f53bcd228a5e_04c173bad44cec04d528d260392958dc6e5bcec3.cab
for backup purposes: h**ps://web.archive.org/web/20210216175344/http://download.windowsupdate.com/c/msdownload/update/driver/drvs/2021/02/0d13721d-7aa7-47cf-887a-f53bcd228a5e_04c173bad44cec04d528d260392958dc6e5bcec3.cab
Direct download and the popup window for 1.6.1015.3014
didn't initially work. I ended up needing to right click the link and select Save target as
.
For it to work for me on Windows 10, I unzipped the cab file into a folder and then used Device Manager to look at that folder. Worked like a charm.
Did you try unpair (not just disconnect) headphones from phone and then pair them to pc ?
Becose if headphones not support multipoint you can connect it only one device.
Did you try to do hard reset headphones and then connect to pc without connecting them to phone first?
In some case deleting headphones driver from windows including hidden drivers also can help.