We have a custom hardware product that uses bluetooth to communicate with an Android application.
Recently we have been getting reports of issues by users that use LG Velvet phones (LM-G900EM). We bought a Velvet and tested it ourselves. The phone will connect to the device, do a service discovery and then disconnect with an error. Usually codes 133(0x85) or 8(0x8).
To verify the issue we connected using the Nordic NRF Connect app instead of our own code. The behaviour is exactly the same.
Attempting the exact same actions on other phones all work perfectly, including other phones running the same version of Android (10) and the same Bluetooth version (5.1) as well as iPhones.
I'm not sure where to even begin addressing this issue. Does anyone have any insight?
This also seems to be an issue on some of the newer ThinQ series phones from LG though we do not have one to verify.
The issue turned out to be the Bluetooth firmware on our hardware. We use Microchip Technology microcontrollers and Bluetooth chips. Upgrading to version 1.4.1 of their firmware fixed the issue.
Apparently this issue also affected certain Xiaomi phones.