If you ever need to change public IP Addresses, follow these steps:
Get the old public IP of the network by going to ipchicken.com or however. Get the soon-to-be IP.
Login to the router’s web GUI through a web browser.
For Checkpoints, you navigate to the “Network – Internet” tab and “Edit” the primary connection. Set the Port to “WAN” and Connection type to “LAN” (for other router’s this may be “DHCP”). Uncheck the “Obtain an IP Automatically” checkbox and enter the IP manually of the NEW IP. For the subnet mask, select the option “255.255.255.252/30” if the ISP only gave the network a specific range. The “Default Gateway” is usually one IP address less than the IP Address.