LAN IP unreachable after CARP failback on VLAN interface

[whph87]

Hi all,

I'm running an OPNsense HA setup (version 25.1) with two nodes: defqon01 (preferred/master) and defqon02.
CARP and pfSync are working as expected — the VIP (10.0.10.1) transitions smoothly between nodes, and state sync is reliable.

However, I'm consistently facing the following issue after failback to defqon01:

⸻

🐞 Problem Summary:
   •   Interface: ix0_vlan10
   •   VIP: 10.0.10.1 (CARP) → works fine
   •   Static IP on LAN interface: 10.0.10.10
   •   After failback from defqon02 to defqon01, VIP is reachable, but 10.0.10.10 is not
   •   ifconfig ix0_vlan10 down && up on defqon01 instantly resolves the issue
   •   Web GUI, ping and other services on the LAN IP remain unreachable until that interface bounce

⸻

🔎 What I've ruled out:
   •   Firewall rules → allow any to 10.0.10.10
   •   Interface is marked UP
   •   IP is bound (seen in ifconfig)
   •   pfSync is working
   •   CARP status transitions as expected
   •   Preemption is enabled
   •   No demotion or failover loops

⸻

📸 Confirmed via:
   •   tail -f /var/log/system.log shows normal CARP MASTER transitions
   •   tcpdump shows no ARP/ICMP replies from LAN IP until bounce
   •   sockstat shows services not binding until interface reset
   •   The issue is 100% reproducible
   •   VLAN interface + CARP seem to be the key