The Internet disappears when you connect two computers

I bought a new router a week ago. Model Tp-link Td-w8961nd. And problems started, when two computers are connected to the router, the internet disappears. One computer is connected by cable, the second by wi-fi. With one computer phones and tablets work. And when you connect two starts to lose connection. And the Internet actually not on the computers, not on the router is not lost.

Answer:

It’s not clear at all what, how, when and where it disappears. Write more details about what exactly happens after connecting the second computer. Does the Internet disappear at once, on all devices? What do you mean by “loss of connection”. And you wrote that the Internet “actually” does not disappear, how? I will try to advise you something, but I don’t understand the problem at all yet.