Thank you for contacting us. I apologize you are not able to stream without buffering on HBO Now and Hulu. It seems you have tried all of the correct steps in order to experience smoother streaming. I have also confirmed the equipment is functioning properly as well. Even though streaming is possible with most services, not every service will stream smoothly due to the inherent latency that comes with satellite internet technology. As an alternative to streaming, I recommend downloading content to your device while connected to the modem via LAN connection. This would allow you to download a movie or show, then play it locally off of the device. You would be able to eliminate any buffering by doing it this way. Here is a link detailing how to do this on most streaming services https://gizmodo.com/how-to-download-everything-from-your-favorite-streaming-1827504636.
As a sort of addendum to what Damian said, PlayOn Cloud seems to be getting more popular. The program/movie is actually streamed from the source (Hulu, HBO Now, etc.) to PlayOn's cloud storage, the process of which uses none of your data. The item is then converted to an mp4 file, which you can then download and watch. There's no buffering, as you're watching it from a fully downloaded file. The actual downloading of the file does use your data. But, you can schedule the file(s) to download during the Bonus Zone, so you can take advantage of that 50GB of data.
You can watch it on any device which you can download the file to and which has a media player that supports mp4 files. Most player do these days. If you have a Smart TV with a USB port, you may even be able to transfer the downloaded mp4 file(s) to a USB flash drive and watch it using your smart TV's built in player.
The PlayOn Cloud app is free to download, and you buy the recording credits. I'm trying it tonight for the first time, and it's working perfectly. Remember, it's PlayOn Cloud you'd want to take a look at, not PlayOn Desktop.
It may be worth taking a look at. https://www.playon.tv/