Multiplying IPv6 addresses with SLAAC network configuration

RouterOS General
1

Not Mikrotik issue, but I hope the community can help.

ISP IPv6 prefix(/64) delegation on my router, this I distributing for clients(Ubuntu 18.04, 20.04 LTS - default network configurations) with SLAAC.
In the first step, I catch 3 IPv6 addresses(Global Unicast IPv6 Address, Temporary and Link Local) on clients.
If the prefix changed, each client gets two new addresses(global, temporary), but the old ones remain and so it’s continues.
How can this be repaired?

2

Set a low value for the RA lifetime in IPv6->ND. It is not a complete fix but at least it makes the problem disappear faster.