I have just installed server, all modules have been activated basics as follows:
Zentyal 5, eth0 external DHCP, eth1 internal fixed, DNS transparent ticked, proxy also transparent. Eth0 is connected to cable modem with ISP specifics, Eth1 is connected to router which is now just a switch. Other computers can access server, but have no internet access (browser blames DNS). You can, however, access internet through Administration interface.
I am almost ready to chuck it and try if I can get Nethserver to work for me.
VBN