Many users face a paradoxical situation: their provider promises 100 Mbps, but when connecting via Wi-Fi, the speed test results barely reach 40-50 Mbps. This isn't magic or malicious intent on the part of the service provider, but the harsh physics of wireless networks and the limitations of their equipment. Wi-Fi speed is always lower than cable speed, and ignoring this fact leads to false conclusions about the quality of the equipment or the honesty of the provider.
The overall performance of your home network is influenced by many factors, from the generation of the wireless standard to the number of neighboring routers clogging up the airwaves. Understanding how router and what channel bandwidth is will help you get the most out of your existing equipment.
In this article, we will take a detailed look at why real indicators differ from theoretical ones, as standards 802.11ac And 802.11ax are changing the rules of the game, and what exactly is limiting the data flow in your apartment.
Theoretical maximum and harsh reality
Router manufacturers like to list impressive numbers on their boxes: AC1200, AX3000, or even N450. However, these numbers represent the combined throughput of all bands and antennas under ideal lab conditions, not the speed you'll get when downloading a movie. Real-world bandwidth always lower than stated due to the overhead of the data transfer protocol.
About 30-40% of airtime is spent on overhead: packet integrity checking, acknowledgement, and collision avoidance. Furthermore, the wireless medium is half-duplex, meaning a device cannot simultaneously transmit and receive data on the same frequency, which automatically cuts the potential speed in half.
It's important to distinguish between bits and bytes. ISP rates and port speeds are measured in megabits per second (Mbps), while download programs display megabytes per second (MBps). There are 8 bits in a byte, so a speed of 100 Mbps in a torrent client will turn into 12.5 MBps.
⚠️ Please note: If your router supports the AC1200 standard, this does not mean a single device will receive 1200 Mbps. This speed is the sum of the speeds of the 2.4 GHz band (up to 300-400 Mbps) and 5 GHz (up to 867 Mbps), and no device can operate in both bands simultaneously.
Below is a table showing the difference between the theoretical limit of the standard and the actual speed that can be obtained "through the air" at a distance of 3-5 meters without walls:
| Wi-Fi standard | Claimed speed (Theory) | Real Speed (Practice) | Typical channel width |
|---|---|---|---|
| 802.11n (Wi-Fi 4) | up to 300 Mbit/s | 80-120 Mbps | 20/40 MHz |
| 802.11ac (Wi-Fi 5) | up to 867 Mbps | 350-500 Mbps | 80 MHz |
| 802.11ax (Wi-Fi 6) | up to 2400 Mbps | 900-1300 Mbps | 160 MHz |
| Gigabit Ethernet | 1000 Mbps | 940-950 Mbps | Cable |
Why isn't the cable speed 1000 Mbps either?
In Ethernet networks, there's the concept of packet header overhead. Even under ideal conditions, a gigabit port physically can't transmit 1000 Mbps of useful user data, as part of the channel is occupied by TCP/IP protocol overhead. The real ceiling for a Gigabit LAN is around 940-950 Mbps.
Impact of the 2.4 GHz and 5 GHz frequency bands
Modern routers are typically dual-band, meaning they broadcast two networks: the good old 2.4 GHz and the faster 5 GHz band. 2.4 GHz It has excellent wall penetration and long range, but it's catastrophically overloaded. Microwaves, Bluetooth headsets, and neighbors' routers are all running through it.
The maximum real-world speed in the 2.4 GHz band rarely exceeds 40-50 Mbps, even if the router supports the N300 standard. This is due to the narrow channel bandwidth and constant packet retransmission due to interference. This band is not suitable for watching 4K video or online gaming.
Range 5 GHz Provides significantly higher data transfer speeds, but has a shorter range and is less effective at penetrating structural walls. This is where rates above 100 Mbps can truly unlock their full potential.
- 📡 Range: 2.4 GHz penetrates 2-3 walls, 5 GHz - one drywall or works within one room.
- 🚦 Workload: On 2.4 GHz there can be up to 15 active neighboring networks, on 5 GHz - usually no more than 3-4.
- 🚀 Potential: For speeds above 100 Mbps, using 5 GHz is mandatory.
If your router supports the technology MU-MIMO, it can communicate with multiple devices in the 5 GHz band simultaneously, which significantly improves the overall network performance when there are many gadgets.
WAN and LAN port limitations
One of the most common bottlenecks that users overlook is the router's physical ports. Even if the wireless module supports gigabit speeds, the WAN input port may be limited to 100 Mbps. This is common in budget router models labeled AC1200.
If your ISP offers internet speeds of 200 or 500 Mbps, and you connect a cable to the FastEthernet port (100 Mbps), you won't be able to go above that speed either via cable or Wi-Fi. Check the specifications for your model: the ports should be marked as Gigabit Ethernet or 10/100/1000 Mbps.
The situation is similar with LAN ports for connecting a PC or console. If you connect your computer via cable to a 100 Mbps port, local file transfers between devices will also be limited to this speed.
⚠️ Important: Make sure your computer's network card also supports gigabit speeds. Older PCs or laptops may have built-in FastEthernet ports (100 Mbps), which will bottleneck even the most powerful router.
To diagnose the connection type, you can check the network adapter status in the operating system. It will indicate connection speed, which will show at what level the devices were physically matched.
The impact of the number of connected devices
A Wi-Fi router is essentially a small computer with a processor and RAM. Each connected device requires resources to operate: NAT tables, traffic encryption, and airtime management. As more devices are added, performance drops for everyone.
The presence of older 802.11b/g devices is especially critical. If even one such device connects to the network, the router is forced to use protection mechanisms that slow down the entire network in order to "understand" the older device. This phenomenon is called protective interval effect.
Background processes also play a role. While you're reading text, your phone might be updating apps, your TV might be buffering 4K content, and your cloud service might be syncing photos. All these streams are combined and divided by the available bandwidth.
- 📱 Smartphones: They often maintain a background connection to instant messengers and social networks, consuming traffic in bursts.
- 📺 Smart TV: When watching videos, they take up almost the entire channel on a permanent basis.
- 💻 PCs and laptops: may create a load when downloading OS or game updates.
To find out who exactly is "eating" your traffic, go to your router's web interface. Usually, in the section Status or Traffic Monitor You can see a list of active clients and the amount of data transferred.
How to check your actual connection speed
To obtain objective data, simply opening a speed test website isn't enough. You need to eliminate the influence of external factors. First, make sure you're in the same room as the router. Second, disconnect all other devices from the Wi-Fi network during the test.
Use trusted services like Speedtest.net or Fast.com. It's best to run tests from different devices to see differences in receivers. It's also worth comparing the speeds over a wired connection and over the air—this will reveal any losses specifically on the wireless side.
When testing, close all programs that may be downloading updates. If you're using a laptop, disable power saving for your network adapter, as power saving mode may reduce Wi-Fi transmit power.
☑️ Speed test
Methods of optimization and speed increase
If your measurements show poor performance, you can improve the situation using software and hardware. The first step is to select a clear channel. In the 2.4 GHz band, use only channels 1, 6, or 11, as they don't overlap. For 5 GHz, it's best to leave the channel on auto-selection or choose the channel with the least congestion.
Increasing the channel width can also provide an increase. In the router settings (usually in the section Wireless Settings or Wi-Fi) You can set the channel width to 40 MHz for 2.4 GHz (if there are few neighbors) and 80 or 160 MHz for 5 GHz. However, a wider channel means a higher chance of picking up interference.
Updating your router's firmware is an important step. Manufacturers frequently release patches that improve connection stability and client-side algorithms. Check the firmware's current status in the section System tools or Administration.
⚠️ Please note: Router interfaces are constantly being updated. Menu item names may differ from those described depending on the model (Keenetic, TP-Link, Asus, Mikrotik) and firmware version. If you don't find the option you need, please consult the official instructions for your specific model.
If software methods don't help, your router may be physically outdated. Models released more than 5-7 years ago simply don't have the computing power to handle modern high-speed streams and encryption.
FAQ: Frequently Asked Questions
Why does Wi-Fi speed drop in the evening?
In the evening, typically from 7:00 PM to 11:00 PM, there is a peak load on the provider's network and on wireless channels in apartment buildings. Neighbors turn on their televisions and routers, creating interference. Furthermore, providers may apply traffic management policies (Shape) during peak hours.
Will a Wi-Fi repeater (amplifier) increase speed?
No, a repeater doesn't add speed; it merely repeats the signal. Furthermore, since a repeater operates in half-duplex mode (receive and transmit), it often reduces the original access point's speed by 50%. For increased coverage without sacrificing speed, it's better to use mesh systems.
Does my provider's tariff affect Wi-Fi speed?
Yes, but only as an upper limit. If you have a 50 Mbps plan, your Wi-Fi won't go faster than 50 Mbps, even if your router supports 1000 Mbps. A router can't create speed out of thin air; it only distributes what your provider provides.
What is 802.11ax and do I need it?
802.11ax Wi-Fi 6 is the latest standard, which performs better when used with a large number of devices. If you have a smart home with dozens of gadgets or many neighbors, upgrading to a Wi-Fi 6 router makes sense. For a single laptop or phone, the difference will be less noticeable.