got this reply from apple review team
Performance - 2.1We discovered one or more bugs in your app when reviewed on iPad running iOS 10.2 on Wi-Fi connected to an IPv6 network.Specifically, on launch, your app displayed the following error message:“Cannot Connect to Emoji Server. Please check your internet connection.”
P.S i ma not using SDWebImage library in my app
http://support.backendless.com/t/ios-app-rejected-when-connected-to-ipv6-connection
Thnaks