Each IPv6 address or IPv6 prefix has a default life time assigned by the server. At certain intervals, a client asks the server to renew its address (called renew/rebind times).
However, if the WAN prefix changes, for example, due to disconnection and reconnection of an Internet connection or a request for a new prefix (Deutsche Telekom Privacy feature), the server has no way to inform the network devices that the prefix or address has changed. This means that a client is still using an old address or an old prefix, and can no longer communicate with the Internet.
As of the LCOS 8.82 version, the DHCPv6 server on IPv6-capable LANCOM devices can require clients in the network to renew their leases/bindings.