According to RFC4291[1], 2001:db8:: is the anycast address for the
prefix and will be answered by all routers responsible for this prefix.
This means that before the iputils bump, the ping from client to isp was
answered by the router and not by the ISP machine. Switching away from
the anycast address fixes this issue.
Credits for finding this go to @primeos.
[1]: https://tools.ietf.org/html/rfc4291#section-2.6.1Fixes#96188
This is a follow-up to the PR #82026 that contains the promised tests.
In this test I am testing if we can properly propagate prefixes received
via DHCPv6 PD with the networkd options in our module system.
The comments in the test should be sufficient to follow the idea and
what is going on.
