Comment 3 for bug 1520517

I am also being affected by this issue, running on Liberty with a ha router.

symptoms exactly like the ones described by toreanderson (ping fine for a few seconds then network is unreachable) ,
I could see the default route being removed at the same time as a number of neighbor advertisements, the route was put back when the next RA was received. Removing the "garp_master_repeat 5" and "garp_master_refresh 10" from the relevant keepalived config fixed the issue.

the problem was encountered with the following address modes:

--ipv6_ra_mode slaac --ipv6-address-mode slaac
and
--ipv6_ra_mode dhcpv6-stateless --ipv6-address-mode dhcpv6-stateless