There should be a bridge mode
Goto Basic -> Network Settings
WAN Port Mode: Bridge Mode
Router IP: Set this to 1 higher than your cable modem. If your cable modem is 192.168.1.1 set Router IP to 192.168.1.2
Subnet mask likely 255.255.255.0
Then set your gateway to your cable modem IP, ie 192.168.1.1
Cable Modem LAN -> 4300 WAN -> 4300 LAN -> your devices