Your router takes the internet signal from your modem and broadcasts it wirelessly
A router is the device that sits between your modem and your devices. The modem receives the internet signal from your internet service provider (ISP) — through a cable, phone line, or fiber connection — and converts it into data your devices can use. The router takes that data from the modem and does two things: it sends it to devices plugged in with ethernet cables, and it broadcasts it wirelessly as WiFi so your phone, laptop, and tablets can connect without wires.
The physical connection is straightforward. An ethernet cable runs from one port on your modem to a port on your router labeled "WAN" (wide area network) or "Internet". The router then creates its own local network — called a LAN (local area network) — that your devices join. Without the router, you would have to plug every device directly into the modem with an ethernet cable, which is impractical for phones and tablets.
Key Takeaways
- The modem connects to your ISP; the router connects to the modem and broadcasts WiFi to your devices.
- An ethernet cable from the modem's output port to the router's WAN port is the only physical connection needed.
- Routers use WiFi standards like WiFi 5 or WiFi 6 to broadcast wirelessly; newer standards are faster but require compatible devices.
- Your router assigns each device a local IP address so they can find each other and send data back through the modem to the internet.
- Routers include a built-in firewall that blocks unwanted traffic from the internet before it reaches your devices.
How the router assigns addresses and routes data
When your phone or laptop connects to your router's WiFi network, the router assigns it a local IP address — something like 192.168.1.5. This address only works inside your home network. The router keeps track of which device has which address, so when data comes back from the internet (a webpage you requested, an email, a video stream), the router knows which device to send it to.
The router also translates between your devices' local addresses and the single public IP address your ISP gave you. When your phone sends a request to Google, the router rewrites the packet to say it came from your public IP address, not from 192.168.1.5. When Google's response comes back to your public IP, the router translates it back and sends it to your phone. This process is called Network Address Translation (NAT), and it is why multiple devices can share one internet connection.
WiFi standards and what they mean for speed
Your router broadcasts WiFi using a standard — currently WiFi 5 (802.11ac) or WiFi 6 (802.11ax) are common in newer routers. The standard determines the maximum speed the connection can reach. WiFi 5 routers can theoretically reach speeds around 1.3 gigabits per second; WiFi 6 routers can reach around 10 gigabits per second. However, the actual speed you see depends on how far you are from the router, how many devices are connected, and what your internet plan actually provides.
Your devices must support the same standard to use those speeds. An older phone that only supports WiFi 4 (802.11n) will connect to a WiFi 6 router, but it will use the older, slower standard. Routers broadcast on two frequency bands — 2.4 GHz and 5 GHz — to balance range and speed. The 2.4 GHz band travels farther through walls but is slower and more crowded; the 5 GHz band is faster but does not travel as far. Many routers broadcast both at once, and your device picks the one with the stronger signal.
The router's firewall and security role
Your router includes a built-in firewall that sits between the internet and your devices. It blocks incoming traffic that you did not request — for example, if a stranger on the internet tries to connect to your computer, the firewall drops the connection. Outgoing traffic from your devices passes through freely. This is why you can browse the web and send emails without the firewall interfering, but someone outside cannot hack into your computer just by knowing your public IP address.
The router also lets you set a WiFi password (called the pre-shared key or PSK) so only people who know the password can connect to your network. Without a password, anyone within range could connect and use your internet. The password is separate from your ISP account password — it only controls who can join your WiFi, not who can change your router settings.
Wired versus wireless connections through the router
Devices connected to the router with an ethernet cable get a direct, stable connection. Desktop computers, game consoles, and streaming boxes often use ethernet because the cable does not drop signal and provides consistent speed. WiFi is more convenient for phones and laptops because you can move around, but the signal weakens with distance and obstacles like walls.
A single router can handle both at once. You might have your desktop plugged in with ethernet while your phone uses WiFi, and they both share the same internet connection through the modem. The router treats them as part of the same local network, so they can see each other and share files if you set that up, even though one uses a cable and one uses radio waves.
What happens when your router loses connection to the modem
If the ethernet cable between the modem and router comes loose, or if the modem loses power or signal from your ISP, the router will still broadcast WiFi — but your devices will not be able to reach the internet. You will see the WiFi network in your list of available networks, and you can connect to it, but web pages will not load and apps will not work. The router itself is fine; the problem is upstream at the modem or ISP.
Restarting the modem usually fixes temporary connection drops. Unplug the modem for 30 seconds, plug it back in, and wait two to three minutes for it to reconnect to your ISP. If the router still shows no internet after that, the problem is likely with your ISP's service in your area, not with your equipment.
Mesh routers and extending WiFi range
A standard router broadcasts from one location, and the signal weakens as you move away. Mesh WiFi systems use multiple units — a main router that connects to the modem, and satellite units placed around your home. All units broadcast the same network name, and your devices automatically switch to whichever unit has the strongest signal as you move. This solves dead zones where the main router's signal does not reach.
Mesh systems cost more than a single router but cover larger homes more evenly. If your home is small or you only need WiFi in one or two rooms, a standard router is usually enough. If you have a large house or thick walls that block signal, mesh may be worth the investment. The modem still connects only to the main mesh unit; the satellites communicate with it wirelessly.
Frequently Asked Questions
Can I use any router with any modem?
Most routers work with most modems as long as they are both the same type — cable modem with cable router, fiber modem with fiber router, and so on. Check your modem's output port type and your router's WAN port type to make sure they match. Some ISPs provide a modem-router combo unit, but you can usually replace it with your own router if you prefer.
Why does my WiFi slow down when I am far from the router?
WiFi signal weakens with distance and obstacles. The farther you are from the router, the weaker the signal your device receives, and the slower the connection speed. Walls, metal, and water also absorb WiFi signals. Moving closer to the router or placing it in a central location usually improves speed. Routers with external antennas often have better range than those with internal antennas.
Do I need to restart my router regularly?
Most routers do not need regular restarts if they are working properly. However, restarting can fix slow speeds or devices that will not connect. Unplug the router for 30 seconds, then plug it back in. Wait a minute for it to fully restart before testing. If you need to restart more than once a month, the router may be overheating or failing.
What is the difference between the WiFi password and my internet password?
The WiFi password (set in your router) controls who can connect to your wireless network. Your internet password (from your ISP) controls access to your account and billing. They are separate. You can change your WiFi password without contacting your ISP, but changing your internet password requires logging into your ISP account.
Can my router affect my internet speed?
Your router can limit speed, but it cannot increase it beyond what your ISP provides. An older router with WiFi 4 will be slower than a newer WiFi 6 router, especially if you have many devices connected. However, if your internet plan is 100 megabits per second, no router will give you more than that. Upgrading the router helps you use the full speed your plan provides.