In this case, your network is probably doing NAT64 or you should be doing it.
For non-HTTPS web there is also: https://www.sixxs.net/tools/gateway/
For non-HTTPS web there is also: https://www.sixxs.net/tools/gateway/
"Not everything is accessible with NAT64, such as SIP, Skype, MSN, and sites with IPv4 literals.[a] However, 464XLAT RFC 6877,[3] which uses NAT64, allows for such protocols over ipv6 only connections."