What is QoS, and What Is It For?

QoS stands for Quality of Service, which means the quality of service. In communications, this phrase refers to the quality of the connection different clients expect to have connected to the same LAN, for example. 

QoS is used, in short, to be able to prioritize specific data traffic to certain clients (with clients, we refer to different devices connected to the same router, be they smartphones, tablets, or computers…).

After all, QoS is a service included in practically all routers offered by internet companies. Although its operation is indifferent depending on the router (based on the same principles to prioritize traffic), it hardly has any effect on low-end routers, despite being implemented as standard. 

Thanks to QoS, if a device uses a large bandwidth (downloading via P2P, for example) and is not assigned as a priority device in QoS, the rest of the clients will be able to continue accessing the Internet at speed according to the one contracted. 

If, on the other hand, that device is assigned as a priority client and the rest are not, you can consume practically all the bandwidth by itself and leave the rest with hardly any connection.

This way, QoS allows prioritizing data traffic between clients connected to the same router, whether connected by WiFi or cable. 

The QoS service is inherent to the router, where all the traffic is centralized, so if there are several routers on the same LAN, the QoS will have to be configured appropriately on each of them.

Nowadays, with FTTH networks, QoS goes to the background since, generally, the bandwidth these networks allow is much wider than with ADSL or WiMAX.

What is QoS used for?

The QoS service prioritises traffic between various devices connected to the same router. With the massive arrival of the gaming world, gamers find it necessary to establish a priority in their computers or smartphones over the rest of the devices that connect to the network. 

This allows you to solve lag problems in games when several devices use the internet through the same router, so it is something to consider if you are a gamer. As we said before, not all routers act equally; in low-end ones, it may not even be noticeable that the QoS is activated and configured.

QoS is also used to prioritize traffic to the same device. Once we select that an internal IP has priority over the rest, it can be further configured in detail so that, in addition, certain types of traffic have priority over others to reach this IP. 

Some medium and high-end routers already incorporate pre-configured algorithms that show us in a list what type of traffic we want to prioritize, such as certain online games (LoL, WoW, Fortnite) or multimedia services such as YouTube, Netflix, and HBO… so the options to configure it according to our needs are comprehensive.

We can also use the QoS service to assign a maximum bandwidth to each device. This translates into limiting the bandwidth of other devices on the network, specifying a host or an IP in the QoS (only if DHCP is disabled, with static IPs). 

In this way, if we have a 100 Mbps connection and limit a device to 10 Mbps, it will never be able to go at a higher speed.

And speaking of speeds, what do you think if you put your internet connection to the test using this speed test?