Everything is working now as expected. The product is just designed to be used with purchased certificates and it has to have a valid chain trust in order to get the product working.
I think it would be better as the person complained on the main announcement post with Let's Encrypt to have both bundles full chain included or simply remove the expired one, there shouldn't be any expired cert in there, even if it's for older android devices. Just thinking.
Anyways, thanks LOADS everything @MikeMcQ @jvanasco and @rg305 for the help here. It was a good long test we did here today 