In plain words
The internet is a chain: your device talks to the router, the router talks to the ISP, and a directory (DNS) translates site names into addresses. When "the internet stops working", a single link has failed. The assistant tests them in order, from the nearest to the furthest, to find which one.
The logic
The first question is the most important: who is affected? It immediately separates router and ISP problems (everyone), device problems (just one) and Wi-Fi problems.
For a single device, the assistant follows the administrators' classic method, layer by layer:
| Test | What it proves if it succeeds |
|---|---|
| The device has a normal IP address | The DHCP server answers |
ping the gateway |
The local network works |
ping 1.1.1.1 |
The way out to the internet works |
ping wikipedia.org |
Name resolution (DNS) works |
| The page loads | The browser and security (certificates, proxy) are fine |
The first test that fails points to the broken link.
Keep a backup connection
Your phone's hotspot lets you consult this assistant, the ISP's status page or its support during the outage.
Going further
The guide Network troubleshooting details each command and its results. To understand the concepts used here: IP address, subnet mask and gateway and Public IP, private IP and NAT. If the problem is slow Wi-Fi rather than no internet, use the slow or unstable Wi-Fi assistant.