When choosing a router in a store or setting up a home network, your eyes often fall on numbers like 300, 1200, or even 6000 Mbps. Many users mistakenly believe this is the actual internet speed at which their smartphones and laptops will operate. However, in the equipment's technical specifications, this value is referred to as total throughput, and it is completely different from what you see in Speedtest.
In fact bandwidth — is the maximum theoretical amount of data that can be transmitted via a wireless interface in one second under ideal conditions. Imagine a wide highway: the number of lanes determines how many cars can travel on it at once, but that doesn't guarantee that they will all travel at the speed limit if there's a traffic jam or poor road conditions ahead.
Understanding the difference between channel width, frequency, and actual throughput is essential for properly configuring a network. In this article, we'll explore how the physics of radio waves affects your speed, why your neighbor's microwave oven might be cutting your internet, and how to select the correct settings in your router's control panel.
Physics of the process: channel width and frequency
To understand where these numbers come from, we need to consider two basic parameters of a radio signal: carrier frequency and channel width. The carrier frequency (2.4 GHz or 5 GHz) is the range in which radio waves operate. Channel width — is the frequency band allocated for data transmission within that range. The wider the channel, the more data can be "packed" into it simultaneously.
Wi-Fi standards vary in channel width. For the 2.4 GHz band, 20 MHz is the standard, with 40 MHz sometimes supported. In the 5 GHz band, channels of 20, 40, 80, and even 160 MHz are available. Increasing channel width directly increases theoretical speed, but this comes at a cost—interference resistance.
Wide channel It's like a wide pipe: it carries more water (data), but if the pressure (signal) is weak or the pipe is contaminated with debris (interference), the flow will become unstable. A narrow channel penetrates walls more reliably and is less susceptible to interference, but it physically cannot provide gigabit speeds.
⚠️ Attention: Setting the maximum channel width (e.g., 80 or 160 MHz) in a densely populated apartment building often has the opposite effect. A wide channel occupies more neighboring networks, increasing the number of collisions and packet retransmissions, which reduces the actual speed.
Wi-Fi standards and their impact on speed
The evolution of wireless technologies has gone hand in hand with growing traffic demands. Each new standard has brought changes to signal encoding methods and spectrum efficiency. It is the standard 802.11n (Wi-Fi 4) was the first to widely implement 40 MHz channel width and MIMO technology, allowing speeds of up to 600 Mbps to be achieved.
With the advent of 802.11ac (Wi-Fi 5) saw a leap into the 5 GHz band. Here, 80 MHz channel width became the de facto standard, with top-end models supporting 160 MHz. This allowed a single antenna to transmit data at speeds of up to 866 Mbps, and when using multiple antennas (3x3 or 4x4), the combined throughput reached several gigabits.
Modern standard 802.11ax Wi-Fi 6 brought not so much an increase in raw speed as it did in improved efficiency under congestion. OFDMA technology allows a single channel to be divided into multiple smaller subchannels, serving dozens of devices simultaneously without sacrificing performance.
The table below shows a comparison of theoretical speeds for different configurations:
| Wi-Fi standard | Range | Channel width | Speed per antenna |
|---|---|---|---|
| 802.11n | 2.4 / 5 GHz | 20/40 MHz | 72.2 / 150 Mbps |
| 802.11ac | 5 GHz | 80 MHz | 433 Mbps |
| 802.11ac | 5 GHz | 160 MHz | 866 Mbps |
| 802.11ax (Wi-Fi 6) | 5 GHz | 160 MHz | 1201 Mbps |
Why is the actual speed always lower than the theoretical one?
In wireless networks, a significant portion of bandwidth is consumed by packet headers, acknowledgements (ACKs), error recovery, and waiting for the airwaves to become available. Actual throughput is typically 50-60% of the advertised speed.
MIMO and MU-MIMO technologies
The most important factor determining the final throughput is the number of antennas. Abbreviation MIMO (Multiple Input Multiple Output) means using multiple transmitting and receiving antennas simultaneously. If one antenna provides a speed of 433 Mbps, then two antennas (2x2) will double this figure to 866 Mbps.
Router specifications often include designations like AC1200 or AX3000. This is the sum of the speeds of all bands and antennas. For example, an AC1200 router typically has one antenna for 2.4 GHz (300 Mbps) and one for 5 GHz (866 Mbps), which adds up to about 1166 Mbps, rounded up to 1200.
Technology MU-MIMO Multi-User MIMO (MIMO) goes further, allowing the router to communicate with multiple devices simultaneously rather than switching between them at breakneck speed. This is critical for scenarios where one user is watching 4K video, another is playing an online game, and a third is downloading files.
Influence of external factors and interference
Theoretical bandwidth is merely a potential, rarely realized to its full potential. Physical obstacles, such as concrete walls, mirrors, and metal structures, absorb or reflect radio signals. The 5 GHz band is particularly susceptible, penetrating obstacles less effectively than the 2.4 GHz band.
There's also the problem of airwave pollution. In apartment buildings, dozens of routers operate on the same frequencies. If your neighbor uses channel 36, and you do too, devices will have to wait their turn to transmit data, which creates latency (ping) and reduces throughput.
Household appliances can also cause interference. Microwave ovens operating at 2.45 GHz create powerful bursts of noise that completely drown out lower-band Wi-Fi. Wireless cameras, Bluetooth headsets, and even wirelessly controlled fairy lights all contribute to signal degradation.
- 📡 Router location: The higher and more central it is, the better the coverage.
- 🔌 Electromagnetic noise: Do not place the router near a microwave oven or powerful power supplies.
- 🏢 Building density: In single-family homes, using the 160 MHz channel width is often not possible due to neighbors.
Setting the channel width in the router
To optimize speed, you need to properly configure the settings in the router's web interface. This is usually done through the "Wireless Network" or "Wi-Fi Settings" section. In most cases, the automatic mode ("Auto") works well, but in challenging conditions, manual settings provide better results.
For the 2.4 GHz range, it is recommended to hard-code the channel width. 20 MHzThis will ensure maximum range and stability, although it will limit speed. Trying to squeeze 40 MHz in this range in urban conditions will almost certainly result in a speed drop due to interference with neighboring networks.
In the 5 GHz band, the situation is different. Here, it's worth trying to set the width 80 MHzIf you have a small number of devices and no neighbors nearby, you can experiment with 160 MHz, but keep in mind that this reduces the number of available non-overlapping channels, increasing the risk of conflicts.
☑️ Wi-Fi Optimization Checklist
How to measure real bandwidth
There's a common misconception that online speed testers (Speedtest, Fast.com) only show your Wi-Fi bandwidth. In reality, they measure your external internet speed, which is limited by your provider's plan. If you have a 100 Mbps plan, the tester will show 100 Mbps, even if your router supports 1200 Mbps.
To measure the actual throughput of a local network (between the router and the device), local tests are required. One of the simplest methods is to transfer a large file over the local network (SMB) and measure the copy time. A more advanced method is to use a utility iperf3.
To work with iperf3 You need to run the server on one device (for example, a PC connected via cable) and the client on the Wi-Fi device being tested. The command to start the server is simple:
iperf3 -sAnd the command for the client that will load the channel:
iperf3 -c 192.168.1.1 -t 30Where 192.168.1.1 — IP address of the server, and -t 30 means the test duration is 30 seconds. The result is in the line Bits per second and will show the actual throughput of your Wi-Fi connection at the moment.
⚠️ Attention: Router manufacturer interfaces are constantly updated. The location of the Channel Width settings may differ from what's described. Look for "Bandwidth," "Channel Size," or "Channel Width" in the wireless settings section.
Frequently asked questions and problems
Why does the router show 300 Mbps, but the Internet is slower?
The 300 Mbps (or higher) figure in the connection status is the connection speed between your device and the router (link speed). Actual internet speed is limited by your provider's plan. Additionally, some speed is lost due to protocol overhead and radio signal quality.
Which is better: one wide channel or several narrow ones?
In multi-apartment buildings, it's best to use multiple narrow, non-overlapping channels (especially in the 2.4 GHz band). This minimizes interference. A wide channel (80-160 MHz) is only useful in a single-family home where you're the only user of the Wi-Fi spectrum.
Does the number of connected devices affect bandwidth?
Yes, directly. The bandwidth is divided among all active clients. If one device is downloading torrents at full speed, the others will only get a small portion of the bandwidth, resulting in lag in games and video buffering.
Do I need to update my Wi-Fi adapter drivers?
Yes, network card manufacturers periodically release updates that improve connection stability and support new encryption standards. An outdated driver may not support 40/80 MHz channel bandwidth, even if the router is distributing it.