Are you trying to acquire the settings file via HTTP or HTTPS
Have you opened or forwarded 80,8411,411,8411 towards the B1 Interface of SBC (depending on preferred ports option
Have you setup the relay in the SBC
Can you browse the settings file in your browser on a PC outside customers network
If you are using TLS then the phone needs to have the root certificate installed on the phone before it can proceed. So you will end up in a loop if you are trying to initially acquire the settings file via HTTPS without the root cert. Root cert SHOULD be found in ipoaddress/WebRootCA.pem and should download it if connecting via HTTP initially