QUICK SUMMARY
Wi-Fi carries digital information between your devices and a nearby router using radio waves. The router then connects that local wireless network to the internet through your modem or internet service equipment.
What happens when you open a website
Your phone or computer turns the request into small packets of data and sends them by radio to the router. The router forwards those packets through your internet connection. When the website responds, the process happens in reverse and your device rebuilds the packets into the page you see.
Why distance and walls matter
Wi-Fi signals weaken as they travel. Thick walls, metal, large appliances, and interference from neighboring networks can reduce speed or create dead zones. A router placed in a central, open location usually reaches more of the home than one hidden in a cabinet or corner.
2.4 GHz, 5 GHz, and 6 GHz
- 2.4 GHz generally reaches farther and passes through obstacles better, but it is often more crowded.
- 5 GHz usually provides faster speeds at shorter distances.
- 6 GHz can provide more open spectrum on compatible devices, but its range is typically shorter.
The practical takeaway
Wi-Fi is the wireless link inside your home; your internet plan is the connection from the router to the wider internet. Improving one does not always improve the other, so test near the router and by Ethernet before blaming the internet provider.
Source
Background reading: U.S. Department of Energy — Radio waves.