Hotline: +420 599 509 599

International business: +420 556 621 020, sales@sectron.cz

The difference between a modem and a router

What Is the Difference Between a Modem and a Router?

Although a modem and a router may look similar, each serves a different purpose. Both are essential devices for connecting to the internet. A modem is not the same as a router, and if you need a reliable internet connection, it’s good to understand the differences between them. In this article, we explain what a modem and a router are and how they differ from each other.

What Is a Modem?

A modem serves as the link between the internet and your computer. It is responsible for converting or translating signals — it modulates and demodulates the internet signal. It converts the computer’s digital signal into an analog one that travels through cable connections, and then changes it back into digital form (ones and zeros) on the receiving end.

A modem can connect to various types of infrastructure - cable, telephone, satellite, or fiber optic.

A wireless modem allows you to connect to the internet wirelessly, without needing cables. This type is often called a WiFi modem.
A cable modem provides an internet connection via cable.

In combination with other devices, such as routers, modems can form a fully functional and connected network that allows us to communicate and access the internet.

Simplified diagram of modem functionality

What Is a Router?

A router is a device that connects multiple networks and directs network traffic between them. It is located between the internet connection and the local network.

Beyond basic data routing, routers can also provide additional features such as network security, Quality of Service (QoS) management for prioritizing specific types of traffic, and firewalls to protect the network from unauthorized access.

A router allows multiple devices to share a single internet connection. The connected devices can communicate with each other using the local network. The router tracks which traffic is going to which device and assigns each device an IP address. It recognizes the destination address of data packets and decides the most efficient path for delivery.

Types of Routers According to Internet Connection

  • Wired routers – connect to the internet using an Ethernet cable. Suitable for fixed connections like DSL, fiber optic, or cable internet.
  • WiFi routers – create a wireless network (WiFi) in addition to wired internet access, enabling cable-free device connection.
  • Mobile routers – connect to the internet through a SIM card with a data plan and create a WiFi network. Ideal for mobile use or areas without fixed connections.


Simplified diagram of router and local network functionality

Comparison: What Each Device Does

  • A modem is responsible for translating the signal, while a router manages transmission, reception, and security.
  • A modem can function alone, while a router depends on a working modem.
  • A router connects devices to the internet only when the modem is active.
  • A modem connects a single device to the internet via an Ethernet cable (or USB connection today). To connect multiple devices, a router must be used.
  • A modem transfers data exactly as it receives it from the internet, without checking it.
  • A router typically includes firewalls to inspect and filter data packets.



Example of a Robustel router

Two-in-One Devices

Nowadays, you don’t necessarily need two separate devices — manufacturers often integrate a modem directly into a router.

Modem vs Router

While a modem serves as a gateway bringing the internet into your home, the router ensures that the connection is efficiently and securely distributed among your various devices.

We will gladly assist you in selecting a suitable modem or router. Contact us at sales@sectron.cz.


Although a modem and a router look like similar devices, each functions differently. A modem is not the same as a router, and if you need a reliable Internet connection, it's good to know the differences between these devices. In this article, we will clarify how a modem and a router differ from each other.

What is a modem?

A modem serves as a connection between the Internet and the computer. It is responsible for translating or converting signals, it modulates and demodulates the internet signal. It converts the digital signal from the computer into an analogue one, which travels through a cable connection and on the other side it converts it back into a digital signal, i.e. ones and zeros.

The modem connects to any type of infrastructure - cable, telephone, satellite or fibre.

A wireless modem allows you to connect to the Internet wirelessly, without the need for cables. This type of modem is also often called a WiFi modem.

A cable modem allows you to connect to the Internet via a cable.

Combined with other devices such as routers, modems can create an overall functioning and connected network that allows us to communicate and access the Internet.

What is a router?

A router is a device that connects multiple networks and it directs the network traffic between them. It is located between the Internet connection and the local network.

It allows multiple devices to be connected to the Internet through a single physical connection. The connected devices can communicate with each other using a local network. A router monitors what traffic goes to a specific device on the network and assigns an IP address to each device.

Routers are divided according to the method of connecting to the Internet


 Wired routers - connect to the Internet using an Ethernet cable. They are suitable for fixed connections such as DSL, fibre optics or cable Internet.

WiFi routers - in addition to a wired Internet connection, they also create a wireless network (WiFi) that allows devices to connect without a cable.

Mobile routers - connect to the Internet via a SIM card with a data plan and create a WiFi network. They are suitable for mobile use or in places without a fixed connection.


Comparison of what each device does

• A modem is responsible for the signal translation and the router is responsible for the signal broadcast, arrival and security.

• A modem can work independently, while the router relies on the modem to work efficiently.

• A router connects a device to the Internet only when the modem is active.

• A modem connects only one device to the Internet using an Ethernet cable or an USB interface. However, if you need to connect more devices, you must use a router.

• A modem transmits data as it receives it from the Internet without checking it.

• A router is in most cases equipped with firewalls that screen data and examine data packets.

Robustel router

Two in one

Nowadays, we don't have to look for two separate devices, but manufacturers can implement the modem directly into the router.

We will be happy to advise you on choosing a suitable modem or router. Contact us at sales@sectron.cz.


ARSY line - creation of websites and e-shops