pfSense

This forum post:
https://forum.pfsense.org/index.php?topic=127585.msg733528#msg733528
Describes what I'm seeing:

This is pretty easy to reproduce.  I just started with a fresh pfsense install.  2.3.4
I have nothing wired to the router except for a single laptop on the LAN port.  WAN is configured for dhcp with no cable connected, so it's "down" and has no address.

Added the following rule (see attached screenshot)
interface: lan
protocol: tcp
source address: *
source ports: * 
Dest.Address: WAN address
Dest Port: 443
NAT IP: 192.168.1.12 - i picked a random address - actually it wasn't random, it was the example address on the rule page :)
NAT port: 443

I did this, applied the filter rules and within a short period of time the laptop was unable to reach the web ui.
From the pfsense console pfctl -d allowed me to reach it again.
Rebooted it and the same thing happened on the reboot.  There definitely appears to be a problem when 'WAN address' is not actually assigned.

The user PiBa has a github pull request that looks like a proper fix for this:
https://github.com/pfsense/pfsense/pull/3782