2016-01-14 Boot-time IPv6 on the homeserver not working
I shutdown and rebooted the homeserver to get an updated kernel and look at some other things. After booting up again I noticed the problem with IPv6 not active on interfaces that started early was happening again. No linklocal addresses configured, no global addresses configured. This affects all ethernet interfaces and ppp0 for the link to the outside world. I also noticed this problem after the upgrade, see Upgrading the homeserver to Ubuntu 12.04 but the problem remains even with an updated kernel (currently 3.2.0-97-generic). I have no idea what causes this and how to fix it. It seems related to Debian bug #726569: haproxy doesn't start on boot due to missing IPv6 address on interface but in that case the address is configured but just not available to applications to bind to. Related Beware the IPv6 DAD Race Condition - Andrew Ayer suggests the same (duplicate address detection race condition) but has disabling duplicate address detection (DAD) as workaround.