I have no Network Manager in Ubuntu server 16.04 LTS, but this bug present.
After booting where is no dhclient in the processes if accept_ra set to 2 and syslog contains
Jun 1 13:55:33 gw dhclient[3663]: PRC: Prefix 2a02:2168:176b:4800::/56 depreferred.
Jun 1 14:05:44 gw dhclient[2762]: PRC: Address 2a02:2168:82d:949::4 depreferred.
if i remove setting accept_ra from sysctl on same leases all works fine except of course DHCP-PD.
I have no Network Manager in Ubuntu server 16.04 LTS, but this bug present.
After booting where is no dhclient in the processes if accept_ra set to 2 and syslog contains
Jun 1 13:55:33 gw dhclient[3663]: PRC: Prefix 2a02:2168: 176b:4800: :/56 depreferred. 82d:949: :4 depreferred.
Jun 1 14:05:44 gw dhclient[2762]: PRC: Address 2a02:2168:
if i remove setting accept_ra from sysctl on same leases all works fine except of course DHCP-PD.