I have some VLANs behind L3 switch (router) on the LAN side of the FW. The firewall LAN interface is defined on the network default VLAN.
On the 22.7 version of the firewall I originally installed, I defined the firewall LAN interface IP address on the default VLAN, and all other internal VLANs IP subnets were defined just as "virtual IP - Other" on LAN interface. I needed some Routes definition also.
I did not define any Outbound NAT rules, all was working OK using automatic Outbound NAT rules (i think through "LAN interfaces" listed on the automatic rule).
I upgraded the FW to 23.1 and all seems to work OK.
These days, I had to define again a new internal VLAN on my network, better to tell: move one VLAN from the FW interface to internal L3 switch.
I deleted the association and the FW interface, I defined the Interface VLAN on the L3 switch. I created the Virtual IP Other definition and the route to reach it on FW.
To do this I repeated the same steps I done few months ago, almost all was working except the ping was not exiting out to WAN, so I made some tcpdump sniffing and I found the new Virtual IP is not NATed automatically like other previously defined VLANs, so I had to place a manual NAT outbound rule. All is working now.
Just not to find other previously defined VLANS stopped to work, I defined them also in outbound NAT rules now.
Feature or bug?
After the upgrade to 23.01, the newly defined Virtual IP (Other) on LAN interface (subnet 192.168.x.0/24) is not Outbound NAT through automatic rule any more. The subnet was before assigned to a VLAN interface, unassigned and deleted. I Had to define a manual Outbund NAT rule for the subnet to get it working.
Before the upgrade, on 22.07, same scenario, all was working as expected, no need for a manual Outbound NAT rule.
I will try to reproduce the error next days.