Hack or just some glitch?

Question

Computer networks

Good day dear experts and amateurs. Help advice and share your opinion who is not difficult. Today I encountered such a problem, with the Internet turned on and working, I could not log into any site. I won’t try to describe the situation and the situation much: An
apartment, it has 2 laptops that work via Wi-Fi, and one PC that is connected directly via a cable, the cable of which is also connected to a router that distributes Wi-Fi.
When working on a PC, without doing anything special, I worked in a text editor, made up a site, for some reason I stopped visiting any sites, it gave an error that the given IP address was not found.
I thought that there was some kind of failure and the first thing I did was restart the computer and the router, but it didn’t help either, I went to the device manager to see if all the equipment was working fine, but everything was fine there. I looked at the Internet connection icon, but everything was fine there too. But then I noticed some strange things, I had some problems in the support center that were either fixed or simply ignored. And my Avast antivirus was turned off, but then in some miraculous way it was launched again without my intervention, all this was noticed and happened in a few seconds. After that, I decided to check if the Internet was working on laptops, but there was the same error when trying to open any site.
But with all this, everyone showed that the Internet connection is working normally and everyone has access to the Internet. It is also strange that on mobile devices the inerent worked normally.
Polo to solve this problem only izminenie DNS.
WHAT COULD IT BE? Specific hack? or the actions of some kind of malware? What steps would you like to take to protect yourself and your data?

Answer 1

for some reason it stopped visiting any sites, it gave an error that the given IP address was not found.

Most likely problems with DNS.
To be more precise, more information is needed.
If it seems to you that the Internet is not working, check what exactly is not working.
Does the address resolve?
DNS ping?
Is the ISP's gateway pinging?