I've updated my 4.9.0-11.12 kernel to include a small patch that hopefully will improve RTL8723BS wifi.
To upgrade your kernel first download the shell script for the kernel version you require and after making it executable (enter 'chmod 755 <script>') you can install it as 'root' (by entering 'sudo <script>'). Once the script has finished executing the device will need to be rebooted to use the updated (patched) kernel.
To get audio running on a Mini PC with a headphone jack using the RT5640 codec (for example Tronsmart Ara) after using a kernel upgrade script simply:
- Open the URL https://github.com/plbossart/UCM in a browser
- Click the green coloured 'Clone or Download' button on the right and download as a 'zip' file
- In a terminal window go to the download directory and enter 'unzip UCM-master.zip'
- Install by entering 'sudo cp -rf UCM-master/bytcr-rt5640 /usr/share/alsa/ucm'