Https:// only works for the latest Crystal version (as of now, only 1.9.2 works), all other versions get timeout issue

Looks like an issue with your connection…

Nope. That’s not related to the user’s connection. It’s an internal error on the sandbox server.
You can visit the same code snippet and you’ll get the exact same result: #g4ff

What is the error? It’s not consistent because rerunning it works fine.

Maybe the server was simply congested?

Yes, it return code 502 or 504 during previous visit.