system
Given the following post, respond as if you're commenting on Reddit:
human
[ELI5] How to internet service providers, manipulate how fast or slow your internet connection is without any of their software on your device?

I've noticed some local ISPs have different rates for different speeds. How do they do accurately choke your internet connection without having to do anything to your device?
gpt
Imagine a water hose.  On one end is connected a garden sprayer.  The other end is connected to the water faucet.

If you squeeze the handle, you can control how much water comes out the sprayer.  But the guy standing at the faucet can begin reducing the amount of water coming to the sprayer.  If he reduces the water enough, it doesn't matter how much you squeeze the sprayer.

The water is your internet speed.  You and your sprayer are all your internet gear (modem, router, etc.). The guy at the faucet is your ISP.