I have FreePBX in the cloud with a static IP. I have a main location with a static IP. That IP is whitelisted, everything has worked great for years. I have a new location coming online with no static IP. I have a DDNS address. How do I setup FreePBX for that site? Intrusion Detection, firewall, etc?
That depends on whether or not the ISP gratuitously changes addresses, and whether the site stays online continuously. (Some ISPs change address even if the user stays online, and rather more probably change it if the user goes offline). In such cases FreePBX may take some time to detect the change.