Default [Q] APN - IPv6 does not work?

I have a rooted LG G2 and as far as I can remember with all my roms, IPv6 LTE APN does not work. Only ipv4. It might be a placebo, but I always felt like the ipv6 provided a better data connection.

I know the setting are correct. I had the exact same setting when I had a SGS4, and some roms come with the IPv6 setting built in, but once selected, no data is established.

Any ideas?