I got IPv6 enabled, and it's nothing but connection issues, I've triple checked all my router settings (mikrotik hAP ac2 with v7 firmware)
It's seems to work for 2-3 days but after that I get timeouts and some connections hang for over 4mins, making page load times god awful and system updates for Linux break.
The only thing that seems to work consistently is to disable ipv6, or restart my routers connection.
I guess this is why it's an opt-in option that's hidden from most users?