Is it possible to remotely control a PC network card using Arduino?

Question

Arduino

Dear electronics gurus,
I have a question, is it possible to make a controlled "network card" using Arduino? That is, the Arduino is connected to the router with one port, and with the other to the computer. Upon the arrival of the command, it breaks the connection with the PC (that is, the Internet disappears on the PC) and vice versa.
Or maybe it can be connected to a PC in some other way and send a PC command through it (remotely, via the Internet) to turn off the network card?
Tell me, please, is something like this real and where is it worth dripping? Thank you!

Answer 1

An Ethernet cable is 4 pairs of cores, that is, 4 relays. Open four relays from arduino - 10 lines of code.
Yes, this can reduce the speed (you have to unwind the pairs, this will add noise), but not significantly, but very simple.

Answer 2

I think it can be done a little differently. Through the Arduino, open the power supply circuit of the router.

Answer 3

Did I understand the diagram correctly? INET<-->Router<--> EthSld1
<->Ard<->EthSld2<-->PC PS: not a guru and not an electronics engineer :)

Answer 4

If the task is to turn off the Internet on the machine, is it not easier to create a schedule for the machine immediately on the router? And if you manage, then in principle you can do remote control on the router, and manage from there.
Another side that you can dig into is andruino via rs-232 to a computer, which simply sends some commands, and write a simple program on the computer that cuts off the Internet with some commands, and cuts it with others.