Some OpenWRT routers like the TL 1043ND I have suffer from VLAN leakage. Basically the router separates WAN from LAN via a VLAN config as the CPU has only one LAN port. At the router's bootup, devices on my lan would randomly get a public IP adress assigned by the DHCP server on the modem. Scared the crap out of me. From now on the thing is an access point, not a router.