For dynamic IPv4 addresses, dynamic DNS services such as Dyn or No-IP are well-known. If an ISP issues a single dynamic IPv4 address every 24 hours (or the like), the router or any other device registers the IPv4 address for a DNS record. With port-forwardings on the router, several services on different clients can be accessed.
Since there are some ISPs that offer dynamic IPv6 prefixes as well, I have a suggestion on how to optimize the “dynamic DNS” service for several IPv6 addresses and names. The main idea is to update only the IPv6 prefix, while the host IDs are statically configured on the DNS server. This limits the DNS updates and expands the usage of DNS names even for devices that have no “DynDNS update client” built-in.