GTA 5 online problems ipv4/ipv6

[bssnik]

A friend has internet trough dual stack lite that means he has only a real ipv6 address and his ipv4 is not real its tunneling through ipv6. Now his problem he can play EVERY game online with me! Really every game but he can't play GTA 5 for a long time, after 45min he get disconnected from Xbox live and he was at Xbox support they can't help him because he can play every game without disconnect only GTA 5 isn't working.. We really don't now, after we played around 30-45min I get disconnected. I hope anyone can help me. I tired vpn tunneling with my win7 laptop and his win XP to connect Ian with Xbox trough his computer but after I opened a vpn he can't connect always error 800.. Maybe anyone can help me..