Mac OS internet network disappears?

Question

Computer networks

Macbook Air 13 "2014.
For a year or two there has been a problem with the network, the Internet suddenly disappears for a couple of minutes. During this period, there were already a variety of OSes, El Capitan, Sirrea, and recently reinstalled completely on the new Sirrea after a complete format. There were different routers and modems, different Internets from different companies, both WiFi and wired Internet - the problem is always the
same.What could be the problem?
The Internet itself works, if it fails, I checked it more than once on other devices.

Answer 1

I have the same problem with PC and Mac did not solve the problem. Changing the router does not help. Contacting support didn't help. I noticed one pattern, it disappears only when there is a body nearby and they call or send SMS