Configuration synchronization (XMLRPC) does not don't replicate the configuration of DHCP relay. relay, neither the igmpproxy configuration. Why? In the same kind but with less impact (because I don't modify these settings everyday): conf sync don't replicate general/advanced configuration (general logging options, enable/disable scrub, enable/disable PF, do not display state table without a filter, etc.). Without that, fresh HA setup requires the utmost attention. Misconfiguration can happen very quickly. Personal example: NFS works when my first XG-1541 is master, not when my secondary pfSense box is master. Why? Scrub disable on first box, enable on secondary box… I have two other personal examples.