pfSense

When using gateway group with failover, dynamic DNS is not updating when the primary link goes down.
Gateway status shows Pending, and gateway group shows Gathering data for that gateway.

Device: SG-3100
Firmware: 22.05

WAN_DHCP: Tier 1 (bridged)
OI_FIBRA_DHCP: Tier 2 (behind a NAT)
Gateway group:: Net_Oi
Firewall default gateway: Net_Oi

Dyndns: Duckdns
Interface to monitor: Net_Oi
Interface to send update from: Net_Oi

Unplug the cable from the primary WAN:
As we can see below, dyndns is not triggered.

dpinger[54273]: WAN_DHCP 179.233.x.x: sendto error: 65
dpinger[54273]: WAN_DHCP 179.233.x.x: sendto error: 65
dpinger[54273]: WAN_DHCP 179.233.x.x: sendto error: 65
dpinger[5605]: send_interval 500ms loss_interval 2000ms time_period 60000ms report_interval 0ms data_len 1 alert_interval 1000ms latency_alarm 500ms loss_alarm 20% dest_addr 179.66.x.x bind_addr 192.168.255.245 identifier "OI_FIBRA_DHCP "
dpinger[54273]: exiting on signal 15
dpinger[54610]: exiting on signal 15
dpinger[54273]: WAN_DHCP 179.233.x.x: sendto error: 65
dpinger[54273]: WAN_DHCP 179.233.x.x: sendto error: 65
php-fpm[454]: /rc.filter_configure_sync: Default gateway setting Interface OI_FIBRA_DHCP Gateway as default.
php-fpm[454]: /rc.filter_configure_sync: Gateway, switch to: OI_FIBRA_DHCP

Plug the cable to the primary WAN:
Now, we can see dyndns being triggered.

dpinger[54405]: send_interval 500ms loss_interval 2000ms time_period 60000ms report_interval 0ms data_len 1 alert_interval 1000ms latency_alarm 500ms loss_alarm 20% dest_addr 179.66.x.x bind_addr 192.168.255.245 identifier "OI_FIBRA_DHCP "
dpinger[54044]: send_interval 500ms loss_interval 2000ms time_period 60000ms report_interval 0ms data_len 1 alert_interval 1000ms latency_alarm 500ms loss_alarm 20% dest_addr 179.233.x.x bind_addr 179.233.x.y identifier "WAN_DHCP "
dpinger[5605]: exiting on signal 15
php-fpm[82104]: /rc.newwanip: Dynamic DNS: updatedns() starting
php-fpm[82104]: /rc.newwanip: Default gateway setting Interface WAN_DHCP Gateway as default.
php-fpm[82104]: /rc.newwanip: Gateway, switch to: WAN_DHCP
php-fpm[82104]: /rc.newwanip: Dynamic DNS custom (): _checkIP() starting.
check_reload_status[468]: updating dyndns wan
dhcpd[67784]: Wrote 0 new dynamic host decls to leases file.
php-fpm[82104]: /rc.newwanip: Dynamic DNS custom (): 179.233.x.y extracted from local system.
php-fpm[82104]: /rc.newwanip: Dynamic DNS custom (): _checkIP() starting.
php-fpm[82104]: /rc.newwanip: Dynamic DNS custom (): _detectChange() starting.
php-fpm[82104]: /rc.newwanip: Dynamic DNS (): running get_failover_interface for NET_Oi. found mvneta2
php-fpm[82104]: /rc.newwanip: phpDynDNS (): No change in my IP address and/or 25 days has not passed. Not updating dynamic DNS entry.
php-fpm[82104]: /rc.newwanip: Dynamic Dns (): Current WAN IP: 179.233.x.y Cached IP: 179.233.x.y
php-fpm[82104]: /rc.newwanip: Dynamic DNS custom (): 179.233.x.y extracted from local system.
php-fpm[752]: /rc.dyndns.update: Dynamic DNS: updatedns() starting
php-fpm[752]: /rc.dyndns.update: Dynamic DNS custom (): _checkIP() starting.
php-fpm[752]: /rc.dyndns.update: Dynamic DNS (): running get_failover_interface for NET_Oi. found mvneta2
php-fpm[752]: /rc.dyndns.update: Dynamic DNS custom (): 179.233.x.y extracted from local system.
php-fpm[752]: /rc.dyndns.update: Dynamic DNS custom (): _detectChange() starting.
php-fpm[752]: /rc.dyndns.update: Dynamic DNS custom (): _checkIP() starting.
php-fpm[82104]: /rc.newwanip: Netgate pfSense Plus package system has detected an IP change or dynamic WAN reconnection - 179.233.x.y -> 179.233.x.y - Restarting packages.
php-fpm[752]: /rc.dyndns.update: phpDynDNS (): No change in my IP address and/or 25 days has not passed. Not updating dynamic DNS entry.
php-fpm[752]: /rc.dyndns.update: Dynamic Dns (): Current WAN IP: 179.233.x.y Cached IP: 179.233.x.y
php-fpm[752]: /rc.dyndns.update: Dynamic DNS custom (): 179.233.x.y extracted from local system.