Looking for logging into the Magento Ipv6 Problem site and are not getting the correct working link for it? In such a case, you can use the links given here by searching your desired login page in the search box. If the page is present on our website then you will get all the links related to the Magento Ipv6 Problem site. After that you can login as usual with your login credentials.
https://github.com/magento/magento2/issues/10249
https://github.com/magento/magento2/issues/10395
http://www.the-mage-expert.com/981/magento-fixing-the-magento-ipv6-problems/
https://magento.stackexchange.com/questions/62386/ipv6-support-for-magento
https://community.magento.com/t5/Installing-Magento-1-x/Can-t-login-into-admin-area/td-p/2196
http://www.der-mage-experte.de/tag/ipv6/
https://www.sitepoint.com/fix-magento-login-issues-cookies-sessions/
https://stackoverflow.com/questions/16960907/how-to-get-remote-ip-address-in-magento/17857647
https://superuser.com/questions/781476/understanding-my-router-ipv6
https://support.plesk.com/hc/en-us/articles/360001508954-Pages-on-a-Magento-website-shows-error-404-Not-found-after-switching-to-Nginx
https://books.google.de/books?id=falAVo8jLlQC&pg=PA407&lpg=PA407&dq=magento+ipv6+login+problem
https://askubuntu.com/questions/14409/how-to-make-scp-to-use-ipv6-addresses
https://serverfault.com/questions/205793/how-can-one-distinguish-the-host-and-the-port-in-an-ipv6-url