@Reaces in my first comment, I said that if I'm unable to do command X, then I'll just stop there, not replying with "I can't use X"

@Reaces My idea was that "do command X" would be useful for future visitors, because they can save a one question to ask. But in retrospect, I think the question cannot belong to them, but is forever stuck with my name. Therefore, even if it saves them times, then the solutions they find cannot give back to the question. I get it now. Thank you

An elaboration on why you don't think it is would be helpful

If I ask about how to use software to detect the possible problem, would that be on-topic?

I think that nails it. Perhaps you may want to include that in your answer

I think that policy is only to prevent off-topic conversations. If comments are used for clarification or more information, as the fade text in the comment box says, then there would be no problem

can you explain more on how Q&A sites won't work like that? What could go wrong, if there is no spiral vortex?

Perhaps I cannot help myself, but gaining more knowledge with give me a better position to discuss with the technician. He has no obligation to help me debug, but if I can show him the possible problem, then probably it will intrigues his curiosity and work with me. And even if it's not possible, questions asking on SE are not solely to help the OP, but also help others. The questions are closed in order to avoid spiral with me only, but for others who actually have root access, they might see them interesting.

I agree with the first two paragraphs, and I agree that the last two ones apply to almost all the cases. However, I acknowledge my limitation and do want to learn, so if the comments just say something like "can you type this command and tell me what you see", then even though I can't do that, I still learn something. The conversation will not commence to spiral, because it will just stop there. I just want you to give me some keywords so I can gain some insight.

In the end I ask this question: Curl returns SSL_ERROR_SYSCALL even though the certificate is correct