Failover host stops releasing IP's if the peer is down.

[p0wn3rs]

Hello,

we have different DHCP clusters and sometimes happens for a system to be 
down for a long time (the location doesn't grant us immediate physical 
access and the hw doesn't support WOL).
Whenever this happens the main host stops releasing IP's...

Dec  9 10:39:36 fw-01 dhcpd: DHCPDISCOVER from 00:a0:ba:0f:d6:ff via 
br1: not responding (recovering)
Dec  9 10:39:37 fw-01 dhcpd: DHCPDISCOVER from 00:a0:ba:0f:d7:29 via 
br1: not responding (recovering)
Dec  9 10:39:39 fw-01 dhcpd: DHCPDISCOVER from 00:a0:ba:0f:d6:ff via 
br1: not responding (recovering)
Dec  9 10:39:41 fw-01 dhcpd: DHCPDISCOVER from 00:a0:ba:0f:d7:29 via 
br1: not responding (recovering)
Dec  9 10:39:43 fw-01 dhcpd: DHCPDISCOVER from 00:a0:ba:0f:d6:ff via 
br1: not responding (recovering)

Configuration :

cat /etc/dhcpd.conf

ddns-update-style none;

deny bootp;

authoritative;

option wpad code 252 = text;

failover peer "CLUSTER" {

     primary;

     mclt 600;

     split 128;

     address 192.168.177.1;

     peer address 192.168.177.2;

     port 519;

     peer port 519;

     max-response-delay 30;

     max-unacked-updates 10;

     load balance max seconds 3;

}

shared-network SERVERS {

     interface br1;

     server-identifier 192.168.18.1;

     subnet 192.168.18.0 netmask 255.255.255.0 {

         pool {

             failover peer "CLUSTER";

             deny dynamic bootp clients;

             range 192.168.18.100 192.168.18.200;

         }

         default-lease-time 3600;

         max-lease-time 7200;

         option subnet-mask 255.255.255.0;

         option domain-name "mydomain.com";

         option routers 192.168.18.1;

         option wpad "http://192.168.18.1/proxy.pac";

         option domain-name-servers 192.168.18.1;

     }

}



lease-file-name "/var/lib/dhcp/dhcpd.leases";

cat /var/lib/dhcp/dhcpd.leases
# The format of this file is documented in the dhcpd.leases(5) manual page.
# This lease file was written by isc-dhcp-4.2.5-P1


failover peer "CLUSTER" state {
   my state recover at 1 2019/12/09 08:52:57;
   partner state unknown-state at 1 2019/12/09 08:52:57;
}

failover peer "CLUSTER" state {
   my state recover at 1 2019/12/09 08:52:57;
   partner state unknown-state at 1 2019/12/09 08:52:57;
}
server-duid "\000\001\000\001%\200\307\351\200\306\312\001\015\354";


failover peer "CLUSTER" state {
   my state recover at 1 2019/12/09 08:52:57;
   partner state unknown-state at 1 2019/12/09 08:52:57;
}

So, the partner state is in "unknown-state" because of course is down, 
but shouldn't the host be releasing IP's after some time?
How can we solve this problem?
thanks,
Robert.