Title: dhcpcd >= 6.4.2 changes defaults for IPv6
Author: William Hubbs <firstname.lastname@example.org>
dhcpcd-6.4.2 and newer supports IPv6 stable private addresses when using
IPv6 stateless address autoconfiguration (SLAAC) as described in
RFC-7217 . The configuration file shipped with dhcpcd activates this
feature by default, because it means that a machine cannot be tracked
across multiple networks since its address will no longer be based on
the hardware address of the interface.
I received a report in testing that IPv6 connectivity was lost due
to this change . If you are concerned about losing IPv6 connectivity,
temporarily comment out the line in dhcpcd.conf that says
"slaac private" until you can adjust to the new configuration.
See the references below for why the upstream default is to use stable
private instead of hardware-based addresses.