pfSense

Dynamic DNS are configured like this:

Interface   Service         Hostname             Cached IP          Description                      Monitored Interface
WAN_1       DNS-O-Matic     ns1.mydomain.com     80.41.32.14        ns1.mydomain.com@WAN_1          WAN_1
WAN_2       DNS-O-Matic     ns2.mydomain.com     90.21.111.73       ns2.mydomain.com@WAN_2          WAN_2
WAN_FO      DNS-O-Matic     nsx.mydomain.com     80.41.32.14        nsx.mydomain.com@WAN_ALL        GW Group WAN_FO

My WAN_FO gateway group is made like this:

Gateway Priority
                    WAN_1_GW    Tier 1
                    WAN_2_GW    Tier 2
Trigger Level
                    Member Down

I've added some logs log_error("###... in the dyndns.class (attached to this report, 3 lines added) to try to understand why dynamic DNS were updating only once my nsx.mydomain.com
Please ignore ipsec_check.sh, it is a simple script to check my IPsec status.
I've an IPSEC configured to work in failover mode over WAN_FO.

To test my WAN failover settings, I manually unplug the incoming fiber.
If you take a look on the log attached, you will see:

• WAN_1_GW is down.
• DynDNS try to update WAN_1 but fails to get a new IP (normal) and complete the updating process.
• DynDNS try to update WAN_FO with success BUT never complete the process, the DDNS2 is never unlocked.
• WAN_1_GW is up.
• DynDNS try to update WAN_1 with success and complete the updating process.
• DynDNS try to update WAN_FO but nothing is done since the DDNS2 is still locked.
• Restarting php-fpm using option 16
• Calling /etc/rc.dyndns.update to force dynamic DNS update

I know that the locking system is a security added to avoid concurrent DNS update.
I don't know how to do step-by-step debugging with pfSense PHP code but I can just say that the updatedns class constructor never reach unlock($dyndnslck); for the Gateway Group related dynamic DNS.
Since we never exit the updatedns class constructor, does that mean that a PHP thread is in a deadlock state or is there an non catched exception somewhere ?