You can simulate bad wifi with the throttling option on the network tab of your browser's developer tools

You can always also simulate bad WiFi by walking away from your access point until you have bad wifi

Slow networks != Bad networks. Bad networks could be slow, or drop random packets, or corrupt packets, or have jitter, etc

That’s an unreliable way of simulating an unreliable network, as overviewed in https://calendar.perfplanet.com/2016/testing-with-realistic-...