What is the Difference Between a Modem and a Router?


Modem and router are often used interchangeably. Whilst often combined in the same hardware entity, they are their own separate devices, each with a specific role. 

Overall, they are both the required connectors in order for any device to communicate with an Internet Service Provider (ISP). The modem connects our local network to the ISP, as the first and most crucial step in accessing internet service. A router is then used in order for the internet connection to be shared with multiple devices within our local network, either via an Ethernet cable or via Wi-Fi. 


One of the main reasons we tend to think of them as one, is because most ISPs provide homes with what is known as a gateway, which is a single hardware device that operates as both a modem and a router.

Therefore, a modem is required to bring Internet to the location it is required (home, office, etc, known as Wide Area Network), and a router is required to disperse the internet connection to all devices within that location (Local Area Network). 

What is a modem?

Modem is short for “modulator-demodulator”. It is the device that connects our local network ISP.  Its primary reason for existence was as a two-way translator of analog signals into digital signals and information from our computers to the ISP and back. Nowadays, translation from analog to digital is not required, and modems function as the connecting port between our devices and our ISP.

Each modem sold has an assigned public IP address that identifies it on the Internet. They then use Dynamic Host Configuration Protocol (DHCP) to assign a master Internet Protocol (IP) address to a local network. Routers will use DHCP and the master address to then assign local IP addresses. 

Most modems have two connection ports: one that connects to the ISP, and an Ethernet port that connects to a computer/laptop or a router. 

There are several types of modem connections:

  • Dial-up (analog modems): Some will remember it from the early days when a phone line was required to connect to an ISP. Nowadays, it will be nearly obsolete.
  • Digital subscriber line (DSL): DSL also uses existing phone lines to connect to an ISP at much higher speeds than dial-up.
  • Cable: The most common type of modem connection, together with DSL. It uses the same cable connection as cable TV. 
  • Satellite: Set up to provide internet connection via satellite dishes. 

A fiber internet connection does not require a modem in its traditional sense, it uses a box called Optical Network Terminal (ONT),which transmits the signals to and fro your ISP using infrared pulses. Fiber cables and a fiber router are required, so the cable connections and router are different to the ones used for the modem connections above. 

The cost of modems are usually included in the internet connection, as an add-on rental. Modems can also be purchased separately, usually together with routers and owning your own can be cost-effective.

However, not all ISPs allow the use of a personal modem or modem/router, so it is important to research and ask carefully before deciding to buy either a modem or choosing an ISP and connection. 

What is a router?

A router is the device that connects to the modem and creates a LAN, allowing all devices to obtain a wired or wireless internet connection. Besides internet connection, the creation of a LAN allows all connected devices to communicate; using a network printer is an example of this.  Routers also assign all devices their own IP addresses, as derived from the modem’s initial IP.  

In addition to those primary functions, modern-day routers provide private network security, firewall protection, and sometimes Virtual Private Network (VPN) connection.

Routers can be wired or wireless, nowadays usually carrying both. This means they will allow Wi-Fi connection to all network devices, and/or could also carry one or more LAN parts in order to connect an Ethernet cable to any local device. To configure a router, you can either open the web user interface or through an app. For example, Tenda router can be configured via the web interface www.tendawifi.com.

Router – Modem combinations

For everyday home consumption, a combined modem-router device is the most practical and preferred solution. There is no question that both a modem and a router are required for any connection. Whether one wants to own a modem and router separately depends on individual preferences, as well as the time and knowledge one has when wanting to install and configure both devices.

When using the gateways provided by our ISP, we can also count on technical support when required, as well as future upgrades and maintenance. If one is not able to undertake their own technical support, then renting or buying from the ISP is the most sensible choice. 

Finally, owning a gateway or a router may not be cost-effective long-term, as rapid changes in technology could render many routers obsolete and prevent us from moving to a faster internet connection with flexibility.

Owning a modem may offer more stability over time; however, if fiber is available and a desirable option for our connection, then this choice could also prove redundant.

Rizwan Ahmad
Rizwan Ahmad

Rizwan is an avid mobile geek and a gaming lover. He loves to keep a tab on new tech and loves to share the latest tech news and reviews on Smartphones, Gadgets, Apps, and more.


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