Just log in to BattleNet. Despite the game being 10 years old Blizzard still is running it. In fact why even use a virtual LAN in the first place, especially since it is slower as the tunnelling adds extra overhead.
Ethernet frames inside other frames, extra overhead of another frame header.
Ethernet frames inside other frames, extra processor time overhead from extraction/generation.
I recon approximately a 20-30% overhead, as there will be at least another full frame copy.
Sure it is mostly trivial, but totally unnecessary when you can just log in to BattleNet and use IPv4 directly to play multiplayer sessions. Well I guess if you only have an IPv6 address it may be necessary but seriously, no one in the UK has one as BT refuses to enable it.