Why does the Internet connection disappear in the browser?

Question

Computer networks

The neighbors began to fall off the Internet. They called me and asked for help.
I climb in, I look, there is a network connection, packets also pass through cmd, without loss. The page does not load in the browser.
I tried to restart the network card, everything worked, but after a while it fell off again, but only in browsers. Skype works and packages pass through cmd quietly.
I thought the network card was throwing it to sleep, I tried to turn it off, but to no avail. After some more digging, I finally gave up. I can't find a causal relationship, but I don't see it. Even if the computer or browser is idle, the Internet still falls off.
Now I ask you for help, because I did not find a solution to my case on the Internet.
Parameters:
A machine with an ethernet cable connected to it through an asus router of the ancient series (they checked it, everything is in order there, besides, Wi-Fi works fine).
WinXP SP3 Prof
Network card (ideally built-in, but DO writes that it is PCIe, or I don't understand something): Realtek PCIe GBE Family Controller.
PS I confess that I don’t understand networks well, so I don’t even get any ideas, I hope for your help.

Answer 1

You must be either a programmer or a computer scientist by profession?)
On the case: if other devices are catching, I would just reinstall the system. This is an ungrateful business, mistakes are still to be found in XP.

Answer 2

There is a network but DNS does not work, specify manually, for example 8.8.8.8 and everything will work.