Magento can encounter issues with IPv6 addresses in several places. The correct solution depends on where the problem occurs, so there is no single fix I can sensibly describe here. If IPv6 addresses are causing trouble in your Magento store, please contact me. I will be happy to help.
Fixing the IPv6 problem
Need help implementing this solution, or still looking for a fix to your Magento problem? Get in touch and I will be happy to help with your project.