Steven, the same thing happens with me. I have great speeds most of the time, but during the evening hours, say between 6 and 9:30 or so, my speeds can go way down to sub 1mb levels, like your chart shows. I imagine it's because that is the time when the most people are on. It just gets bogged down. I should say I HOPE that's the reason, as the alternative isn't a very good one (deliberate throttling during those times), nor likely, I hope.
During those times I can still surf just fine, and I wait until it speeds back up if I have to do anything that requires decent bandwidth.
To add, that's just my experience. I'm not trying to lessen the importance, nor validity, of your frustration.
Also, I've only had Gen4 for a week, so I don't know if this is the norm, or something recent, but I have been with Hughesnet since 2004, and had experienced something similar a while back on my original Pro plan, though it got better.
Any updates? Speed is as bad as ever. Why is Hughes Net charging me so much $ for a 10 Mbps plan when I only get 1 Kbs in the evenings (90% less than I am paying for). Not even close to the promised, advertised speed. And keep in mind this is an evening thing. Anyone telling me my speeds are ok is not checking my evening speeds.
Last year, I filed a complaint with the Maryland Attorney General Consumer Protection Division and sent letters to the Hughes Net President as well. Subsequently, I was contacted by a high level Hughes Net customer service rep and afterwards my speeds rose to acceptable levels. As a result, I then asked the Attorney General to put my complaint on hold. But the good speeds only lasted a couple of months. Then they crashed again. This has been going on for two years. I cannot accept this anymore. The Maryland Attorney General's office asked me to contact them and they would re-open my case if things got worse... and that us what I plan to do in April if things do not improve.
So let me know if anyone is really working on improving my download speeds. i.e. a status report.