Your app crashed on iPad or iPhone running iOS 11.2.5 connected to an IPv6 network but Why?

Question

One of version of an app rejected with this message Your app crashed on iPad or iPhone running iOS 11.2.5 connected to an IPv6 network . The problem is the application has not a single network function or functionality so I am unable to understand whats going on.

This was the 4th version of application, old versions was on store. At last version we just removed an issue causing the application fail text to speech in new iOS versions.

Answer 1

I wrote a similar note to the Apple and they approved application after sometime. I think problem was not my application this time.