ISC DHCP Server Failover

 Documenting this as it was driving me insane, couldnt find any help online

Ubuntu 18.04 and 20.04

Errors in syslog

Oct 19 07:24:32 control dhcpd[13024]: DHCPDISCOVER from 40:a3:6b:c1:25:20 via ens160: not responding (recovering)

Oct 19 07:24:32 control dhcpd[13024]: DHCPDISCOVER from 60:01:94:e4:0b:a6 via ens160: not responding (recovering)

Oct 19 07:24:32 control dhcpd[13024]: DHCPREQUEST for 192.168.1.132 from d8:31:34:f2:e3:ad via ens160: not responding (recovering)

All I needed to do was the let ISC-DHCP-Server use the default ports:

failover peer "failover-partner" {
    primary;
    address 192.168.1.62;
    # port 519;

    peer address 192.168.1.172;
    # peer port 520;
    mclt 3600; # Primary only
    split 128; # Primary Only
    max-response-delay 60;
    max-unacked-updates 10;

    load balance max seconds 3;
}