What does the rejection say, exactly?
Does 'doesn't work' mean works but fails, or simply not compliant?
You should check out my Supporting IPv6-only Networks pinned post, and specifically the first section of the post linked to by FAQ #6.
Also, DTS’s standard advice for problems like this is contained in:
Technote 2431 App Testing Guide
Share and Enjoy
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware
let myEmail = "eskimo" + "1" + "@apple.com"