HTTPS: Is it allowed or not?

In the thread posted in 2014, Lyqyd claimed that ComputerCraft does, in fact, allow you to use HTTPS to connect to a server. He said that because GitHub requires it, and we can get code from GitHub, we should be able to use https, which makes since. However, in my program for OnlineAPPS, you can NOT use SSL in the Minecraft version of ComputerCraft, as the HTTPS request returns with nil, although http.checkURL returns that it is valid. I've had to make a "test" https request to test if it allows it, which in most cases, it does not. (The only version I've found that does is CCEmuRedux) Does ComputerCraft only allow certain CA's?

Twijn, on 13 November 2016 - 04:23 AM said:

Does ComputerCraft only allow certain CA's?

TLS does work with some websites, and fails with others, ComputerCraft doesn't tell why these websites fails, on the other hand, OpenComputers does give more insights…

Spoiler

It's indeed about which CA is used, though both of those mods doesn't use their own list of valid CAs, instead they use Java's list, so this is a Java problem.
The site I used in my example is signed with Let's Encrypt, and it appears your website is too.