“My internet is down.” It’s a simple statement that could mean half a dozen different things — each with a different cause and a different fix. The internet coming into your home passes through several pieces of equipment before it reaches your computer, and a problem at any one of those points looks the same from where you’re sitting: nothing works.

Understanding the basic chain of how your connection gets to your device is one of the most practically useful things you can know.

The modem

The modem is the box that connects your home to the internet service your provider delivers — through a cable, a phone line, or a fiber optic connection. It’s the point where the outside world meets your house. Usually provided by your internet provider, sometimes owned by you.

When the modem has a problem, nothing in the house has internet — not your computer, not your phone, not your TV. Everything fails together. If that’s what you’re experiencing, the modem — or the line coming into it — is where to look first.

The router

The router takes the single internet connection from the modem and shares it among all the devices in your home. It also creates your wifi network — the signal your devices connect to wirelessly. Most homes today have a combined modem-router in a single box, but the two functions are distinct.

When the router has a problem, devices may still be able to connect to each other on the local network, but nothing can reach the internet. Or the wifi signal may disappear entirely while a computer plugged in with a cable still works fine.

Wifi vs. wired — a real difference

Wifi is convenient. It’s also inherently less reliable than a physical cable. A wireless signal has to travel through walls, floors, and air — and it competes with signals from neighboring networks, cordless phones, microwaves, and every other wireless device in range. The further you are from the router, and the more obstacles between you and it, the weaker and less stable the signal.

Many problems that present as “slow internet” or “internet keeps dropping” are actually wifi problems — not problems with the internet service itself. The connection coming into the house is fine. The wireless signal reaching the device isn’t.

A simple test: if you can plug your computer directly into the router with a cable and the problem goes away, the issue is the wifi, not the internet. That points toward either router placement, router age, or interference — all of which have solutions that don’t involve calling your internet provider.

When a cable is the answer

For any device that stays in one place — a desktop computer, a TV used for streaming, a printer — a wired connection is almost always the better choice. Faster, more stable, less susceptible to interference, and one fewer variable when something goes wrong. The inconvenience of running a cable is a one-time cost. The reliability benefit is permanent.

People default to wifi because it’s easy. But if you’ve ever had a video call drop, a streaming show buffer, or a large file transfer crawl — and the device was on wifi — plugging in a cable is worth trying before anything else.

Signal reach and dead zones

A router placed in one corner of a house — often wherever the cable comes in, which is rarely the most convenient location — may not reach reliably to the far end. Thick walls, multiple floors, and building materials all absorb signal. If your internet works fine near the router and poorly on the other side of the house, you don’t have an internet problem. You have a coverage problem.

Solutions range from moving the router to a more central location, to adding a wifi extender, to a mesh network system that places multiple access points throughout the home. The right answer depends on the size and layout of the space.