That is so annoying and disappointing. I don't know what to do about this either, because if it hates the certificate because it was issued for being a wildcard there won't be much that I can do. I suspect that this will change in the future, but it looks like some android users may be out of luck for now. Thank you for letting me know about it, I'll talk to my certificate authority. For what we paid for, we were promised 99.9% browser support, though, so I'm legitimately pissed off now if this is an issue for ALL android devices on 6.x or lower.
I wonder if it is accepted by Android 7.x branch.