How many devices do you have connected to the modem (edit: directly or via wifi)? Have you tried streaming while connected directly to the modem?
OK, so you don't have a phone connected to the wifi, or a computer, or a tablet, etc.?
Have you tried streaming while going to the site directly? (example, by going to Netflix).
Have you power cycled the modem?
That was a troubleshooting step, not a suggestion that you change how you stream. If you could, you should connect your PC directly to the modem and try to stream with the PC.
If the HN reps see nothing on their side when they check, this means the issue is on your side, and troubleshooting is needed to figure out what it might be.