If one computer of the network is turned off, then the Internet on the other disappears. What is it?

Question

Computer networks

Network: modem -> wi-fi router ASUS RT-N14U -> 2 laptops: Dell (Win 10 x64), Samsung (Win 10 x64) + plus phones, tablets.
The last week there has been a net drop when the Samsung laptop is turned off (and only when this laptop is turned off). Moreover, all the indicators, both on the modem and router, and in the OS, show that everything is working, but there is no Internet (bad gateway). Only restarting the router helps.
The new software was not installed. Only system and antivirus updates.
Help, please, to define the reason of such behavior of a network.

Answer 1

First, try to reflash to the latest firmware (even if it's already the latest one) Reconfigure the
router.
If it doesn't help, then you need to dig further.

Answer 2

The problem is in the router, set the provider settings manually.