Have you ever visited or tried to log into a website, and been greeted by odd error messages like "Access Denied" or "Oops something went wrong". Your thinking "What the heck? I'm just trying to use your site as it was intended". Then you figure the site must be having some type of technical issue, and either move on, or try back later. Well, even if you try back later for days you still get the same errors. Then you turn off your VPN, magically the site works perfectly fine. This is your first introduction into the world of banned service providers AKA black/block lists
I will preface this by saying that the examples below were tested on one of the the largest VPN providers out there. You might or might not have issues using your VPN provider, but weird errors are something to keep in mind when sites just seem to break, and you can't figure out why. It might look to you like the site is broken, but this is just the site designers way of protecting themselves from abuse.
When you see all of these errors, odd messages, or connection issues, much of it is done on purpose. Websites will setup security services or appliances to block connections from networks that give them issues or cause trouble. VPN providers or large hosting services like Amazon usually end up on these lists. VPN's and hosting providers are services people can hide behind to abuse websites. This abusive behaivor is something the websites don't want to deal with. They will throw up a message or error to let you know that there was an issue. They will never tell you what that issue was, nor will they likely ever tell you that you have been blocked. If they did this then an attacker might change tactics or providers to see if they can get through another way. That is the worst part of this process. The site won't tell you it's messing with you, it will just make it look like it has broken itself in a gentle and annoying way. From the websites point of view, it's just protecting itself.
Sites perform all kinds of antics when encountering IP's they don't trust. For example ...
Note: All sites below work perfectly fine with VPN off. These errors only happen with VPN on.
Hopefully you don't encounter these issues with your VPN provider. But if one day you start seeing odd problems with a website, and you just can't figure out what's going on, always try to turn your VPN off if you have one. If your seeing one of the type of issues above, and you are not using a VPN, then you might just be on a block of IP address's from a provider that is causing grief for certain websites. If that happens, this is where a VPN might be able to help you. If you can find a VPN that has not been marked as troublesome by the same website your having issue with, then you can use it to access the site. Go figure.