Do you even know what the internet is? Because if you knew what the internet was, you wouldn't be asking this question.
One does not simply "turn off" the internet.
Discussion
You ask that question, because it’s a philosophical one. The answer might be quite insightful.
You might be confused, because as you stated correctly, if you look at it from a technical standpoint, there has to be a planet ending event to „turn off“ the internet. But we are not all engineers and programmers on here, are we?
No, we are not all engineers and programmers, we are also not all physicists, but gravity still affects us and a non-physicist still cannot fly.
I wasn't trying to be snarky, I was prompting to pique your interest in the hopes you would search/ask a more interesting question like "why can't we simply turn off the internet".
If I ask: "if I found the gold at the end of the rainbow, how rich would I be?"
Do you follow the premise that there is gold at the end of the rainbow and make up an answer, or do you correct the premise in the hopes of addressing the misunderstanding that lead to the question that otherwise makes little sense other than as a fictional one.