Up to iOS 11 I have used a technique where the ipv4only.arpa. domain is used to retrieve its address info. From this if the address family is AF_INET6 it is possible to extract a prefix that can be used to form a valid IPv6 address when you only have an IPv4 address. This has worked well and is necessary because the network has only IPv4 addresses and no DNS for the routing from outside the network.
Now the getaddressinfo() returns a NULL address. Apple hinted that the IPv4 address lookup would be unavailable in iOS 11, and that appears to be true.
But I need help understanding how to resolve this issue because it is unlikely the the network affected, will be changed to provide DNS or IPv6 any time soon, and this could affect several million users.
Does anyone else have a technique for this that might work with iOS 11 or if Apple catches this, a suggestion on how to pursue a solution to the problem.