What to do if download and upload speed drops on a laptop?

Question

WiFi

My girlfriend started complaining about lag in games a month ago. I found out that the problem is in ping. It constantly stays on for about 40ms, but sometimes jumps 150-300ms. This was not the case before. I decided to see what the speedtest would give me at home. The first 2-3 times speedtest gave a normal speed of 100 downloads and 85 downloads (About the same numbers I get from a desktop computer). But for 4 times the laptop gave 35 downloads and 25 downloads. My computer has never had such drawdowns. The Internet is connected via WI-FI.
I'm not asking for a specific solution, at least I need a hint where to look and what to check?

Answer 1

Well, WiFi. The neighbor turns on the microwave - and you have a drawdown.
The solution is simple - you need stability - we pull the cable

Answer 2

A neighbor appeared on the same Wi-Fi channel, which is actively pumping
evenly The router dies / overheats

Answer 3

We need a larger sample than 4 measurements.

Answer 4

I don't think you get the point. The bottom line is that the Wi-Fi in my house works fine on all devices, but on the computer that I brought the same result is not.