I understand that you are having some issues in order to set up your Slingbox Classic for Internet Viewing.
Most of the times, this issue is related to the settings to adjust on the router. You need to gather the IP address provided by the router for your Slingbox and create the port forwarding rule. Once you follow this process, your Slingbox will be able to reach the Internet and you will be able to get the remote connection. Even though you do not have a Slingbox SOLO, the instructions included on this link guide you through this process:
Even though this router model is not listed, the following third-party link will provide you with the steps to follow in order to adjust the router settings for Internet Viewing: