The scenario
Laptop (192.168.1.100/24) is connected to WiFi-Router; the cable in this lab stands in for the WiFi link. The address is fine, but the default gateway was set to 192.168.1.99, and no device on the network has that address. The real router is 192.168.1.1. It translates the laptop's traffic to its internet-side address, 203.0.113.10, and beyond it Internet (203.0.113.1) is a web server on TCP port 80. Laptop can reach anything on 192.168.1.0/24, but nothing further. There is no DHCP server in this lab: Laptop's address and gateway are set on Laptop directly.
What you will work out
Understand why 'connected' does not mean 'online', and how to spot and fix a wrong default gateway.
Why this matters
'Connected, no internet' is one of the most common complaints a help desk hears, and a wrong gateway is one of its causes. The check takes seconds: look at the default route ('ip route' on Linux, 'ipconfig' on Windows), confirm the gateway is on your own subnet, and confirm a router really answers at that address. If the settings came from DHCP, fix the DHCP server's configuration, or every device will keep getting the wrong gateway.
Running it
WiFi Connected But No Internet opens on a canvas, already wired and addressed. Trace a packet through it hop by hop, or run the same topology live on real Linux network namespaces. How the two modes differ.
Open WiFi Connected But No Internet
Runs in your browser. No install, no signup, and the simulation starts instantly.
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