I'm having the *exact* same issue, from roughly the exact same time as you (1/24/2020, started roughly 7pm EST). I cannot connect to Discord (website, desktop app, or mobile app) on any device. Hulu doesn't connect, and a number of other sites I use regularly are suddenly unable to connect. Occasionally I get a "your internet access has been blocked" error but that usually gets replaced with "site can't be reached" errors upon refresh or restart. I can confirm all of these sites are safe to visit, and they all work just fine on my 4G network. However, I can't access them at all via wireless or ethernet wired connections while on my home network.
I've also noticed that some sites that *do* load seem to be loading very slowly despite my speed test seeming fine. Netflix, in particular, is taking a very long time to load show thumbnails, and the video streams often start out grainy or pixellated.
This is extremely frustrating for me for two reasons. First, I upgraded to Gigablast service just this past Wednesday (1/25) so I was hoping for a much smoother internet experience overall. Second, I work from home, and a number of sites I need access to regularly are suddenly inaccessible. It's really important for me to have these sites available, but it's been close to 24 hours since the issue arose. Something is definitely up on Cox's end.