Browsers/Mail :: Internet Refusing To Load Webpages?

My internet is currently not loading pages properly since I starting using a Telsta modem that came with the internet bundle (T-Box and Modem set). My D-Link modem stopped working due to old age I guess and doesn't turn on anymore. So I set-up the Telstra modem (with the included filter that I was using on my old modem, the D-Link and pages were loading fine).

For example when I try to load Facebook sometimes or Twitch.tv it does not load the page, sometimes only the text-based version on Facebook and Twitch.tv but sometimes on Facebook images and video's don't load. But on Youtube it works fine and loads videos perfectly like my old modem does. But some / most websites don't load.

I think I am close to being capped (but not sure why that would allow Youtube videos to load in 720 / 1080p)