ASUS RT-AC86U Firmware version 3.0.0.4.386.44470
1. Improved system stability.
2. Added IPv6+ in WAN-> Internet Connection.
3. Added Auto firmware upgrade in Administration-->Firwmare Upgrade
4. Fixed envrams exposed issue. Thanks for Quentin Kaiser from IoT Inspector Research Lab contribution.

RT-AC86UでIPv6+なる項目が追加
これが日本のv6プラスをさしているかは不明