I think that what Keef is getting at is that you cannot have both the Netcomm and the Netgear acting as
DHCP servers.
What you should end up with is the WAN / uplink port on the Netgear connected to the Ethernet port on the Netcomm. Then the computers connect to the netgear LAN ports or via Wireless.
It is probably easiest to use the Netcomm as the DHCP server, in which case you will need to turn OFF the DHCP service in the Netgear (it's in the manual). Advanced / Lan settings
Note that you may also have to specify a fixed IP address for the Netgear that is within the same subnet as the Netcomm. By default, the Netcomm uses 192.168.1.0/24 (the /24 means a 24-bit subnet mask - i.e. 255.255.255.0) as the network, while Netgear uses 192.168.0.0/24.
So, assuming that the Netcomm Ethernet port is 192.168.1.1, you would need to set the Netgear IP address to 192.168.1.2, then ensure that the DHCP scope on the Netcomm starts from 192.168.1.3 (or higher).
The Netgear is then effectivley acting purely as a switch (with an internal bridge connecting it to its wireless network). You may as well switch off the firewall on the netgear, as the firewall functionality is on the Netcomm.
All this is in the manuals for the Netcomm and Netgear devices, btw.
SD