Hey, thank you for the birthday wishes! That’s very thoughtful and I really appreciate it! 
And you’re welcome, for sure. There are times when I get frustrated, too. I don’t use Windows, so I run into a whole slew of issues that very few people here ever see. I really know the feeling. I sit down…try to get ready to start a new game lesson, and then BOOM! VS Code doesn’t want to open and I have to spend the next two hours troubleshooting Unity problems. For real…in fact, this was me last week:
…and this was me the week before:
The struggle is real, yo.
Anyway, it seems like you have a good understanding of what I wrote about, so let me ask…would it be safe to assume that you have the knowledge to step through the OSI Model and the TCP/IP model to rule out the website itself? 
I don’t mean anything bad by that, I really don’t.
I really think we’re on the right track with a CORS issue. I’m sure you’re aware that there are many types of servers, and in this case let’s consider a web server that serves up web pages, and a file server that serves up video content. I’m sure you already see where I’m going with this. That file server, or related infrastructure, might be the issue. Even though it looks like a Layer 7 issue, it could really be hardware issue (and not a network issue at all) if the file server is down or if a RAID drive crashed. The 422 error would very likely appear the same to the network.
It could be temporary, or in the process of being fixed. It could be something of which the provider is unaware at the moment.
The fact that you can watch Udemy videos tells me it’s probably not your host browser. I had to take a break from my troubleshooting and go to Taekwondo, but I was thinking about it while I was out and I remember that detail now.
Also, GameDev.tv is run through Teachable, as you mentioned already, which I would consider to be more of a PaaS, but maybe some people think of it as SaaS. Either way, GameDev.tv is the customer at this point, renting someone else’s platform and infrastructure.
Moving forward, I would consider a few different approaches, depending on how much you like to get your hands dirty.
-
Migrate your courses to Udemy and take them through the Udemy platform, as you asked about at the beginning. That’s probably the easiest way.
-
I’d have to research and remember how to do this, but if you already know…you could probably change your DNS server settings and try to hit a different GameDev.tv server and see if that makes a difference. It’s not ideal, but it might work.
-
You might contact Teachable and share your details and ask if they have an expired security certificate, or something of that nature. I mean, it could be as simple as that, but who really knows at this point in time? It might be something they need to look into based on their servers and your location. To go this route, I would recommend that you ping the gamedev site and report that specific IP address to Teachable, along with the rest of the details, and then they would be better able to chase down the offending infrastructure using the IP address.
If this is the case, remember, it’s the PaaS, and not necessarily GameDev as a website. GameDev is the customer, too, and they would have every right to be angry with Teachable for having angry students.
At this point in time, I’m convinced it is Teachable’s problem, or whomever’s infrastructure that Teachable is renting. It’s very likely that Teachable does not own their own servers, either. Teachable might be renting server spaces around the world to host their platform…maybe AWS or Google, etc.
I did mention some other edge cases like China and DoS attacks. I don’t like to rule out any possibilities when I’m troubleshooting, but most edge cases could easily be eliminated, as I’m sure you’re aware. Let’s just move on from those.
The other people offering suggestions were trying to help out as best as they know how, and there’s nothing wrong with that. I’m not bragging, but I’m A+ and Network+ certified, and I’ve been studying the Cisco Network Technician material for weeks now and I’m prepping for my CCNA exam, so I’m thinking about this kind of stuff all day long. I’m not a good programmer…I’m just kind of a different breed. I’m here for fun, and to learn how to be a better programmer.
I would venture a guess that most of the people here are not network technicians or troubleshooters by nature, however, many of them are great programmers and wonderful artists! They really are doing their best to help out using what they know.
I will say this with all sincerity, this is a great community and it’s really the only online community that I like. That’s mostly because the people here are really great and super helpful, and there is a strong emphasis on being polite and respectful. There are a lot of kids in this forum, and it’s important to display good values to them, as well as being respectful to our peers.
This is honestly the only online forum that I really like. I mean, I use Twitter and LinkedIn as well, but I don’t know any people on either of those sites and I don’t engage directly with people on those sites anywhere near as much because people can just be rude to strangers on the internet for no reason and I just don’t think it’s cool. The people here have always treated me with dignity and respect, and I really appreciate it.
I really hope you grow to like this place better, too, and I hope to see you in the forum more often!
Lemme know if you ever have any other questions or concerns and I’ll see what I can do to help.
Welcome back!