Modem vs. Router Which One Should You Buy- Welcome to MERCUSYS

If you want to set up the internet at home or in your office, you will likely come across two important devices: the modem and the router. Many people mix them up or think they do the same job, but each device has a different role in how your internet connection works.

Understanding the difference can help you choose the right equipment and avoid wasting money on something you don’t need.

What Is a Modem?

A modem is the device that connects your home network to your Internet Service Provider (ISP). It takes the signal coming through your cable, phone line, or fiber connection and translates it into data your devices can understand. The word ‘modem’ comes from ‘modulator-demodulator,’ which describes how it converts digital data to analog signals and back.

For example, if you have cable internet, your modem receives the signal from the cable jack and delivers internet access to one device. On its own, a modem does not create a wireless network or connect multiple devices.

There are different types of modems, such as:

DSL modem: Uses a phone line.
Cable modem: Uses a coaxial cable.
Fiber modem (ONT): Used for fiber optic internet.

You can buy a modem or get one from your ISP if it's compatible.

What Is a Router?

A router is a device that takes the internet connection from your modem and shares it with other devices in your home or office. Routers can create a local network, which means your phone, laptop, smart TV, and other devices can all connect to the internet and to each other.

A router usually has:

Ethernet ports for wired connections
Wi-Fi antennas to broadcast a wireless signal
Security features like a firewall and encryption

Without a router, only one device can use the internet connection from the modem. If you want Wi-Fi or want to connect more than one device, you need a router.

Modem vs. Router: Main Differences

It’s easy to confuse the two because they often sit next to each other, and many ISPs now offer combined modem-router devices. But here are the main differences:

Function: The modem connects to the Internet. The router distributes that connection to your devices.
Connectivity: A modem talks to your ISP. A router talks to your devices.
Network: The modem does not create a local network. The router does.
Security: Routers usually have security settings, while modems don’t.

Do You Need Both?

In most homes, you need both a modem and a router. The modem brings the internet into your house, and the router shares it with all your devices. However, there are some cases where you might only need one:

Only one wired device: If you just want to connect a single computer via Ethernet and don’t need Wi-Fi, you can plug it straight into the modem.
Integrated device: Many ISPs provide a gateway that combines both functions into one box.

Using separate devices can give you more flexibility and control. For example, you can upgrade your router for better Wi-Fi without replacing your modem.

Modem-Router Combo Devices

A modem-router combo (often called a gateway) is a single device that has both modem and router functions. These are convenient and take up less space. ISPs often rent these units to customers.

Pros of a combo unit:

Easier setup
Fewer cables
One device to troubleshoot

Cons:

Limited features compared to standalone routers
Harder to upgrade
If one part fails, you have to replace the whole unit

If you value simplicity, a combo device might be a good choice. If you want more advanced settings or faster Wi-Fi, separate devices are usually better.

How Does a Modem Provide Internet Access?

A modem (short for modulator-demodulator) provides internet access by converting digital signals from your device into signals that can travel over your internet provider’s infrastructure (such as cable, DSL, fiber, or satellite)—and vice versa.

A modem enables internet access by:

Linking your home to your ISP
Translating digital signals into internet-ready formats
Receiving a public IP address for online communication
Delivering data to your local network or devices

What Is A Gateway?

A gateway is a networking device or node that acts as a bridge between two different networks, often with different protocols. It enables data to flow between networks that otherwise couldn’t communicate directly—for example, between your local home network and the internet.

Which One Should You Buy?

Here’s how to decide:

If you are setting up internet for the first time: Check if your ISP provides a modem. If so, you might only need to buy a router.
If you already have a modem: You only need a router to add Wi-Fi and connect multiple devices.
If you want better performance: Consider buying separate modem and router units so you can upgrade them independently.
If you prefer convenience: A modem-router combo is simpler and easier to manage.

When buying, always make sure the modem is compatible with your ISP’s network. For the router, consider features like:

Wi-Fi 6 support for faster speeds
Dual-band or tri-band capabilities
Parental controls and security settings
Enough Ethernet ports for your devices

Tips for Setting Up Your Network

Regardless if you use a combo device or separate units, follow these tips:

Place the router in a central location to get the best Wi-Fi coverage.
Update the firmware to keep your network secure.
Change the default passwords on both devices.
Use strong encryption like WPA3 for Wi-Fi networks.

Should You Rent Or Buy Your Router?

Deciding whether to rent or buy your router depends on your budget, technical comfort level, and how long you plan to stay with your current internet service provider (ISP). If you stay with your ISP for more than a year, buying is usually cheaper.

Renting could be more practical if you're not tech-savvy or prefer unrestricted involvement. You should rent if you want a simple setup and free tech support, you're only staying with your ISP short-term (e.g., under a year), and you don’t need high-speed Wi-Fi or advanced features.

Final Thoughts

The modem and router each play an important role in connecting your devices to the internet. Choosing the right setup depends on your internet service, your home layout, and how many devices you plan to connect.

Knowing how these devices work helps you make better buying and home network setup decisions. Mercusys offers reliable and affordable networking products that help you build fast, secure connections for any home or office.

No matter if you need a high-speed Wi-Fi 6 router or a simple modem, we have a range of devices to fit your needs. Browse our website to explore options that will make your network smooth, secure, and ready for the future.

Here are our recommended routers from Mercusys:

MR80X (AX3000 Wi-Fi 6 Router): Dual-band Wi-Fi 6 with combined speeds up to 3 Gbps with MU-MIMO, OFDMA, Beamforming, 4 high-gain antennas, and full Gigabit WAN/LAN.

MR50G (AC1900 Wireless Dual Band Gigabit Router): It is equipped with 6 high-gain antennas, MU-MIMO, Beamforming, and Gigabit ports. The MR50G router is also ideal for HD streaming and gaming.

MR47BE (BE9300 Tri-Band Wi-Fi 7 Router): Tri-band Wi-Fi 7 delivering up to 9.3 Gbps (2.4/5/6 GHz bands). It includes 2.5 Gbps WAN/LAN and six omnidirectional antennas.