As per the many disclaimers on the HughesNet website and the subscriber agreement, speeds and performance are not guaranteed. Speeds are going to be heavily influenced by the inherent nature of satellite internet, plus a lot of other factors, such as network congestion, internet latency, and others. So while most users get the advertised speeds and more delivered to their modem, the other factors impact what happens next.
To have speed issues addressed by the reps in this community, first you will need to follow the procedure detailed here: https://community.hughesnet.com/t5/Tech-Support/Think-you-have-slow-speeds/m-p/110034#M74607
For more information on running these tests, check this page: https://support.hughesnet.com/en/faq/internet/how-check-your-speed-performance
EDIT: you should also check to see if you've run out of your monthly data allotment.