Our update has been rejected twice today for ipv6 network connectivity issues. Our networking code has not changed between the previous release and this current release.
We ran into similar situation. Our app was rejected due to connectivity problems in IPv6 networks. Also our servers are using AWS.
I've performed Test for IPv6 DNS64/NAT64 without any issue on my side, and we decide to submit an appeal to this rejection.
We explained that the test on our side was finished with success and that we are using AWS infrastructure.
After two more days the app was again reviewed and accepted