Well, so we got some progress.
Yes, you should disable the internal network router's dhcp and let lmce take care of it.
Try following:
If you have a hub, try plugging it to the internal network nic (eth1). Plug any device to it and see if you can accesse the internet from it.
If it does, then lmce is routing from the internal to the external network and your problem is the internal router configuration.
To verify if the routing capability is enabled, do:
sudo cat /proc/sys/net/ipv4/ip_forward
if the return is 1, the routing capability is enabled.
if the return is 0, than do:
sudo echo 1 > /proc/sys/net/ipv4/ip_forward
and test if you get access to the internet from the inside network.
BTW, the ip forward is enabled in the /usr/pluto/bin/Network_Firewall.sh, by the command echo 1 >/proc/sys/net/ipv4/ip_forward
Check it.
Please report so i can keep helping you.