Web GUI fails to start with Virtual IPs on LAN: Address already in use

[ssbarnea]

I managed to find a configuration setup that while resonable will render your opnsense webgui useless as it will fail to restart.

How to reproduce?

    install haproxy
    add a Virtual IP for your LAN (192.168.33.1 in my case)
    configure haproxy to use that virtual-ip (192.168.33.2 in my case)
    restart web gui (or wait till next day)
    enjoy not having a web gui anymore and not being able to start the service at all.

Thus is why I raised a bug on https://github.com/opnsense/core/issues/3419


I have no idea how to avoid this case and it seems to be another variation of the old bug where there was an option to bind to all interfaces. Now you can only pick one interface, but if you happen to add multipe IPs to that interface you are back to the same problem.... where you endup being locked out of web gui.