DHCP(dynamic host control protocol): when ISP will give you DHCP service than you will setup below this way.
WAN Site configure(step1-step2):
Step1: IP > DHCP Client > ether1 >Apply >OK
Step2: IP > DHCP Client + interface=ether1> Apply > OK
LAN Site Configure (Step1-Step2):
IP > address+ (Must be put LAN IP address such as 172.16.0.1/24) > select ether5
Step1: IP > DHCP Server > Select ether5 > Next > Next > Finish
