ZCC Ipv6 issue on Singtel ISP

Hi All,

Do you experience DNS issue with few ISP for eg Singtel (But not all users of it) home wifi.
On user system it has assigned Ipv4 address with dns and Ipv6 address but no v6 dns from ISP router.

And system has zcc and dns is terribly slow.

Moment logged off from zcc dns lookups become quick.