I recently acquired a cisco 881w router, and it seems to be working pretty good so far, except I've been running into problems with the Zone Based Firewall, particularly for DHCP on my WAN Interface. I have a CM100 Cable Modem (ISP = Comcast), plugged into my FastEthernet4 port (for WAN), and I configured that port with "Ip Address DHCP" and "No Shutdown". I have also set up NAT Overload for my inside devices to use the internet.
The problem is that after my Zone Based Firewall (Low) is setup, I lose my IP Address on my WAN interface.. It just disappears.. Same if I restart the router.
I checked my zone based firewall rules, and there is a entry for "outside >> inside, Allow BOOTPC" so my WAN interface should be able to get an IP Address right?
Attached is my running-config.