ENDIAN Firewall

It also works bad for me. The main problem is that this is an horrible tweak.
Endian (and many other Linux-based firewall appliances) should have more than 3 internal zones (GREEN, BLUE and ORANGE is not enough on some setups).
Having two interfaces bridged and afterwards unbridging them via iptables and rules is awful.

Check if you have more than 1 Endian working on the same network.
We found out that if we use two endians with more than one card (or VLAN) on any zone, it makes a loop between them, and collapses the whole network.
I.e. we had two endians with GREEN as eth0 and eth1. As they are bridging both interfaces, any broadcast/multicast received from eth0 is replied to eth1.... and the other Endian did the opposite.
We took down our network this way. Since then we added some broadcast storm on switches and such, but it's really a problem on Endian to use more than one NIC/VLAN on each zone, and a bigger problem to have two Endians with that setup on the same network.