First, the connectivity issue. It's possible that there is inclement weather at your gateway location. Your gateway is your entrance point to the internet, and it's on the "other side" of the satellite from your own location. Your signal goes from your dish to the satellite and down to the gateway, where it then connects to the internet. It can be anywhere in the US, but it's most likely out west. If it is weather related, it should only be temporary. With that said, one thing you can try is resetting the modem. Disconnect the power AT THE WALL PLUG, wait for about a minute, then plug it back in. If the modem is still in the same state a few minutes after reconnecting the power, it may very well be weather at the gateway, and if that's the case, again, it should just be temporary.
With regard to the video streaming, have you tried turning off the Video Data Saver? The Video Data Saver is designed to save data by throttling the speed of a streaming service to something amenable to SD, but if the streaming service can't, or doesn't, self adjust the streaming resolution, it can cause buffering issues. You can turn the VDS off to see if that makes any difference. You can do so through the Video Settings tab in the HughesNet Usage Meter, or by signing in to the HughesNet myAccount site and clicking on the Settings tab. You can find the site here... http://my.hughesnet.com/myaccount
Keep in mind that streaming is a VERY data intensive activity, and it's quite easy to exhaust all of your data if you are not careful, especially if you stream in HD.
Also, make sure that you are not out of data, which you can see in the HughesNet Usage Meter, or by signing in to the same HughesNet myAccount site and clicking on the Usage tab. You can also view it at the top right of this HughesNet Support Community page by clicking on My Usage (you have to be signed in).