When someone is on an IPv6 network with an MDM solution specifying a per-app VPN then Qt cannot make any network calls in this setup

When someone is on an IPv6 network with an MDM solution specifying a per-app VPN then Qt cannot make any network calls in this setup, often throwing network error 3 (Host Not Found) and sometimes 99 (Unknown). Network calls that use Apple's networking stack directly seem to be working fine.

The network API used in this case is QNetworkRequest and QNetworkReply. It works when using Apple's Foundation networking classes natively: NSURLSession and the like.