How WiFi speed is distributed among devices: the full picture

Many users experience a situation where the internet works perfectly when only one laptop is connected, but the situation changes dramatically with the addition of a smartphone or tablet. It feels like the speed "disappears" or is split evenly, like a slice of pizza that everyone gets a smaller portion of. However, the mechanism for distributing traffic in wireless networks Wi-Fi is much more complex than a simple arithmetic division of the channel bandwidth by the number of connected gadgets.

In reality, a router isn't a static allocator that rigidly sets limits for each client. Instead, it acts as a manager, assessing the needs, priorities, and technical capabilities of each connected device in real time. Understanding these processes is key to eliminating lag when watching 4K video or lag in online games when someone in the family is simply scrolling through a social media feed.

Modern communication standards such as Wi-Fi 6 or Wi-Fi 6E, are offering new traffic management algorithms that are radically different from how routers operated ten years ago. In this article, we'll take a detailed look at the physical and logical aspects of bandwidth distribution, examine the impact of frequency bands, and answer the question of why your device may be receiving less speed than advertised by your provider.

Physical limitations and channel capacity

The whole system is based on the concept bandwidth Bandwidth, which represents the maximum amount of data transmitted over a communication channel per unit of time. Imagine a wide highway: the number of lanes on it is the theoretical maximum, but the actual speed depends on many factors, including the quality of the asphalt, the weather, and the number of cars. In the world of Wi-Fi, the "highway" is the radio channel, and the "cars" are the data packets that must be delivered from the router to the client and back.

It is important to understand that the speed stated on the router box, for example, AC1200 or AX3000, is the combined theoretical value for all bands and antennas. The actual speed you get on a specific device is always lower due to protocol overhead, signal strength, and, of course, airtime competition. If one device starts actively downloading files, it takes up a significant portion of the airtime, leaving other devices with only short windows to transmit their packets.

⚠️ Please note: The actual wireless connection speed under ideal conditions is typically no more than 60-70% of the theoretical standard speed. Don't expect to get 867 Mbps on an 80 MHz channel in an urban area with dozens of neighboring networks.

The physical connection layer also dictates its own rules: the farther a device is from the router or the more obstacles (walls, mirrors, household appliances) in its path, the lower the modulation rate. The router is forced to switch to lower, but more reliable, data transfer rates for the remote client, which automatically increases the time required for that device to transmit the same amount of information. This time is "eaten up" from the overall pool of available airtime for all other users.

Time-sharing and packet queuing principle

The key mechanism that determines how wifi speed is distributed among devices is a time-sharing technology known as TDM (Time Division Multiplexing) in a broader sense, or, more precisely for Wi-Fi, a method of multiple access with carrier sense and collision avoidance (CSMA/CA). Unlike wired Ethernet, where devices can transmit data simultaneously over different pairs of cable, in a wireless environment, only one device can "talk" at a time. The router switches between clients at incredible speed, creating the illusion that everyone is working simultaneously.

Each device gets its own "timeslot"—a microscopic chunk of time during which it can transmit data. If you have ten smartphones connected, the router allocates each approximately one-tenth of the airtime, but that doesn't mean the speed will drop exactly tenfold. The speed will drop proportionally to how actively each device uses its time slot. If nine devices are simply online and transmitting only service packets, while the tenth is downloading a movie, it will take up almost all the available timeslots.

The packet queue plays a crucial role here. The router creates a queue for outgoing traffic, and the scheduling algorithm determines which packet will be sent next. In the default settings, the principle FIFO (First In, First Out) — "first in, first out." This means that a heavy file that starts downloading first can block lighter requests from other devices, causing lag (ping) in games or video buffering.

• 📉 Competition for airwaves: Each device must "wait for silence" on the air before sending, which creates natural delays as the number of clients increases.
• ⏱️ Transfer time: Slow devices (such as those with the 802.11n standard) take longer to transmit the same amount of data than modern Wi-Fi 6 devices.
• 🔄 Context switching: The router spends processor resources switching between clients, which can become a bottleneck if there are a very large number of them.

The Impact of Wi-Fi Standards and Frequency Bands

Wireless standards are evolving, and each new generation (802.11ac, 802.11ax) brings its own resource allocation mechanisms. Older routers that only operate in the 2.4 GHz band often become a bottleneck due to the narrow channel and high levels of interference. This band has only three non-overlapping channels, and if your neighbors are also using them, the efficiency of speed distribution drops dramatically.

Transition to the 5 GHz band and implementation of technology MU-MIMO Multi-User Multiple Input Multiple Output (MU-MIMO) was a revolutionary step. While a traditional router communicates with devices one at a time (SU-MIMO), MU-MIMO technology allows data to be transmitted to multiple devices simultaneously. This radically changes how Wi-Fi speed is distributed among devices: instead of waiting their turn in the general stream, devices receive dedicated data streams in parallel.

However, it's worth remembering that MU-MIMO only works for data transmission from the router to the client (downlink) and requires support from both devices. If your router supports it, Wi-Fi 6, but the smartphone was released five years ago, they will communicate using the old rules, and the benefits of the new standard for this particular connection will not be realized. Furthermore, new routers use the technology OFDMA (Orthogonal Frequency-Division Multiple Access), which allows one channel to be divided into many smaller subchannels, transmitting data to different devices within a single time interval.

⚠️ Please note: Router settings interfaces are constantly updated by manufacturers. Feature names like "Smart Connect" or "Airtime Fairness" may differ or be moved to other menu sections. Always consult the official documentation for your model.

Traffic prioritization and QoS

When it comes to why Skype or Zoom lags when downloading updates, we're faced with a lack of proper prioritization. By default, the router treats all data packets equally: bits from a video call are no more important than bits from a background torrent download. To solve this problem, there's a technology called QoS (Quality of Service), which allows you to set priorities for certain types of traffic or specific devices.

Modern routers often feature "Game Mode" or "Multimedia Priority" features that automatically detect traffic types and prioritize them. You can manually configure rules so that the laptop hosting the video conference receives the maximum available bandwidth, even if other devices are actively consuming traffic. This doesn't increase overall bandwidth, but it does redistribute it toward mission-critical tasks.

There are two main approaches to implementing QoS: port/protocol-based and device-based. The first method marks packets of certain types (for example, VoIP or HTTPS) as high priority. The second method strictly reserves a portion of the channel for a specific MAC address. The second approach is more reliable in home environments, where it's important to ensure the stable operation of a specific smart TV or workstation.

The "slow client" problem and the impact of older devices

One of the most hidden, yet critical, problems in speed distribution is the "slow client" effect. The Wi-Fi protocol is designed in such a way that the data transfer rate in the network is often adjusted to the capabilities of the weakest participant, especially in older standards. If your powerful router Asus or Keenetic When an older smartphone with the 802.11g standard is connected, the router is forced to spend more time transmitting data to this device, using more stable but slower signal encoding methods.

This phenomenon is called the "penalty for legacy clients." While the router communicates at low speeds with an older device, all other devices are forced to wait for airtime to become available. In fact, a single older device can degrade the overall performance of the entire network by taking up a disproportionate amount of airtime to transmit small amounts of data.

The solution to this problem is the function Airtime Fairness (Airtime Fairness), a feature found in many modern routers, prevents slow devices from hogging the airwaves by artificially limiting their transmission time so that faster clients don't suffer. Without this feature, the only solution is to create a guest network for older devices or completely eliminate them from the main network.

How to check which device is slowing down the network?

Log in to your router's web interface and find the "Client List" or "Traffic Monitor" section. Pay attention to the "Link Speed" and current load columns. A device with a speed of 54 Mbps or 150 Mbps on a network where others are running at 866+ Mbps is a potential culprit for reduced overall performance.

Dual-band routers and load balancing

Modern routers are dual- or tri-band, operating simultaneously in 2.4 GHz and 5 GHz frequencies (and even 6 GHz in Wi-Fi 6E). Users often combine these bands under a single network name (SSID), relying on the feature Band Steering (band management). The router automatically decides which band to assign the device to based on its capabilities and current load.

However, Band Steering algorithms don't always work perfectly. Sometimes a router can force a powerful laptop into the crowded 2.4 GHz band because it perceives the signal as stronger there, even though the speed would be much higher in 5 GHz. In such cases, manual network separation (for example, HomeWiFi And HomeWiFi_5G) gives the user complete control over how speed is distributed. You decide which devices will access the high-speed 5 GHz highway and which will remain on the 2.4 GHz "backroad."

Load balancing also depends on the number of antennas and streams. If a router has a 2x2 configuration, it can handle two data streams simultaneously. Tri-band routers often dedicate one 5 GHz band exclusively to communication between mesh system satellites, leaving the other two for clients, which significantly improves resource allocation in larger homes.

Frequently Asked Questions (FAQ)

Does Wi-Fi speed decrease proportionally to the number of connected devices?

No, it's not necessarily proportional. Speed ​​depends on the activity of the devices. If 20 devices are connected, but 19 of them are sleeping or transmitting only occasional heartbeat signals, the speed for the active device will barely change. A drop occurs when devices start actively consuming traffic simultaneously.

Will replacing the router with a more powerful one increase the speed?

Yes, if your current router can't handle the number of clients or uses an older standard (e.g., 802.11n). A new router with support Wi-Fi 6 More efficiently manages queues and airtime, allowing more devices to operate comfortably even under high load.

Can a miner or virus on one computer slow down Wi-Fi for everyone?

Absolutely. If one device on the network is infected and participating in a botnet or mining, it creates a constant high load on the network. Without QoS or speed limits enabled for that specific IP/MAC address, it will consume almost all available bandwidth, leaving other users without internet access.

Why is the speed on my phone higher than on my laptop, even though they are located next to each other?

This is due to differences in wireless modules. A smartphone may support a wider channel (for example, 80 MHz versus 40 MHz on a laptop) or have a more modern antenna system (2x2 MIMO versus 1x1). Also, the laptop's Wi-Fi drivers may be outdated or configured for power saving, limiting speed.