The limitation is the switch does not support vlan.

question
1.  is this possible to have different subnet like i would like certain pc to have subnet 192.168.1.1 - 62/255.255.255.192
  to use WAN1 gateway only?
2.  i have a dhcp with range 192.168.1.100 - 200, how to have another dhcp on LAN with a set of dhcp 192.168.1.1 - 62/255.255.255.192 which will be assigned based on MAC address?

if the above is not possible, any alternative.

Thanks