If what you state is correct and nothing was changed in the DL806 then it's time for a call to Mackie. I haven't dealt with my DL1608 for a couple of years. Last sync issue post was
http://cacophony.aspinock.covm/e. index.php?topic=520.msg15172#msg15172
Since the X-Air era three years ago I haven't looked back. If you need to send it in for service as I understand it buying a XR18 it will be cheaper.
In the future if you need help please be specific (iPad version, iOS version, MF version etc.) otherwise were throwing darts.