With an IPv6 connection you can reach every device directly via ist IPv6 address if the access is allowed in the router.
With the DDNS sub hosts you can create further addresses (camera.example.feste-ip.net or server.example.feste-ip.net) for your host name (example.feste-ip.net). If your IPv6 prefix changes, these names will be refreshed automatically, too.
The sub hosts are combined with the particular main name. If this signals a new IPv6 address, all sub hosts will be refreshed with the new prefix automatically.
The sub hosts also can be used as goals for our portmapper.
The add-on IPv6 sub hosts extends your DNS name to have the opportunity of activating devices in your network directly without port forwarding.
Deposit in your account in host details -> IPv6 Features just a name and so-called "Interface Identifier" of the device. With every change of the prefix of the network the new host name will be refreshed automatically.
"Interface Identifier" is host part of the IPv6 address.
You can find this with Windows via ipconfig; with Linux via ifconfig and with many other devices in the configuration.
The maintenance of the sub hosts assumes every device, which shall be directed via subhost, are located in the same part of network.
This could be if you established your IPv6 connection via tunnel broker.
With the use of DS Lite your router is located in another part of network as your local devices (prefix).
Please, go on reading here, how you can use sub hosts nonetheless!