It may well be that with a newer version your Wolfson card no longer works, that’s true. However, if you have a separate SD card with which you could test a new image, it would be worth a try. I am very sure that with a fresh stretch image WLAN should work. If this is the case, you can then try to install the Wolfson card on this image.
By the way, you can find information about your image in the web interface under „Settings/Reboot“ –> Debug Info.