Why does the speed drop when connecting a laptop?

Question

ADSL

I know that a problem often occurs when the speed drops when connected to Wi-fi.
But my case is completely different. I came home, connected the laptop to the Internet, the speed is small, 14 Kb / s. Yandex opens 3 minutes. Then it turned out that on a stationary computer the speed is normal (when a laptop is not connected), the PC is connected to the modem via a wire, I think it’s okay, it’s probably about wi-fi, I connected a laptop via a wire, and there is also no speed. And here the most interesting thing is if a stationary computer is connected. over the wire, you start the connection speed test, it shows normal speed, at that moment you connect the laptop via the second wire or through the wafer, it doesn’t matter, and then the speed drops on ALL devices, turn off the laptop, the speed returns. Nothing swings on the laptop, Windows 10. All other phone tablet devices work fine through the waffle. It turns out simply when connecting a laptop through any network connection, the speed just drops to zero on all connected devices. I seem to be pretty good at computers, but I have no idea what it is. The only thing that comes to mind is a virus.
I saw that the Internet sucks, but these services are not removed, what should I do?

Answer 1

Look at the network load on the laptop using the task manager and sniffers, if the virus sends something over the network, you will see.

Answer 2

>>and then the speed drops on ALL devices.
The first candidate for suspicion: you have incorrectly configured Internet connection sharing (ics) - turn off ic sharing in the properties of each network adapter.
if that doesn't fix it, see wireshark what kind of traffic is going through the adapter.
and yet - judging by the consumption of memory, it looks like you do not have enough of it.

Answer 3

and you can fix it. do I have exactly the same picture?