Encountering the same problem. I have a legacy Solo unit and am using Safari on an iMAC. As with you, other devices both on and off my network operate normally.
When I go to online setup it indicates I have the latest update, and when I go to the "Set Up Internet Viewing" option it 'sees' and displays audio and video processing.
Looking for solution.
Have you tried allowing the SlingPlayer plug-in to run? The forum post linked below will show you how to allow the SlingPlayer to run on your Mac computer. Others have tried it and had success. I would recommend trying this as well:
Hope this helps!