My domain name has both IPv4 and IPv6 addresses assigned.
IPv4 connection to Google can't be available all the time due to restrictions of my campus network,
but IPv6 is available all the time.
Google fails to access my site when IPv4 connection is not available,
so I think Google is using IPv4 address only, when crawling my site.
How to make Google crawl my site using IPv6 address when my domain name has both IPv4 and IPv6 addresses?