A standard method for configuring the Edge appliance is to use private 10.x.x.x space between the Edge appliance and the WAN1 gateway router.
REQUIREMENT: You must have direct access to the WAN1 gateway router, and it should be local to the Edge appliance.
Steps for configuration:
1) Configure WAN1 of the Edge appliance with (example) 10.0.0.2/255.255.255.250, the gateway address should be 10.0.0.1.
2) Configure the LAN address with the old gateway router address (example) 220.127.116.11/255.255.255.0
3) Configure the gateway router with 10.0.0.1/255.255.255.250
4) Add a static route for 18.104.22.168/255.255.255.0 via 10.0.0.2
5) Test the routing and make sure that Edge firewall is allowing traffic through.