[BUG] FSockets and IPv6 networks

Hello, our team is working in a mobile multiplayer game ([link][1]).

We are about to launch a external test flight on IOS but Apple rejected our app because 'is not IPv6 capable", here the message:

“We discovered one or more bugs in
your app when reviewed on iPhone and
iPad running iOS 10.3 on Wi-Fi
connected to an IPv6 network.”

“To resolve this issue, please run
your app on a device while connected
to an IPv6 network (all apps must
support IPv6) to identify any issues,
then revise and resubmit your app for
review.”

We’re followed the Apple’s IPv6 netwok guide ([link][2]) and we was able to reproduce the issue as is described next:

In order to understand our problem i’ll explain how our servers works.

  • The client (ue) connects with our backend.
  • After the socket connection is established we send the login credentials.
  • The backend validates the petition and send the response back.

It works perfect if using a IPv4 network connection, but it fails using a IPv6 one, and it is mandatory regarding the new apple IPv6 policy ([link][3]).

The issue:

  • [Scoket->GetConnectionState()] returns [SCS_Connected] so the socket is supposed to be connected.
  • Anyways when the client send the login credentials the packet fails, to be clear [ Server->Send(…)] returns [FALSE].

To take in consideration:

  • Engine version: 4.14.3 (source), [modified][5].

  • Our sockets are implemented according this [link][4].

  • The backend is running in a windows machine (AWS EC2 with Windows Server 2012 Standard, supporting IPv4 and IPv6 networks)

  • The backend sockets supports dual mode.

132383-tcpview.jpg

Possible related issue:

  • [Dedicated server connection issues with IPv6 networks][7]

Hello HDardis,

Thank you for reporting this issue. I’m currently looking into getting a test set up for this but due to the network modifications required, it’s taking some time. I’ll try to get back to you as soon as possible.

Hello HDardis, I apologize for the delay on this response; Are you still experiencing this issue? If so, I would like to continue looking into it.