The situation when a wired connection Ethernet shows performance lower than a wireless signal Wi-FiThis seems like a paradox. By definition, the cable standard should provide stability and maximum throughput, unattainable by radio waves in noisy environments. However, users often encounter speed tests that show the opposite, leading to confusion and suspicions of equipment malfunction.
Such speed imbalances rarely occur out of nowhere and almost always indicate a specific technical issue or network misconfiguration. This could be due to physical damage to the twisted pair cable, outdated network cards, or specific router settings that prioritize wireless traffic. Understanding the nature of this phenomenon is the first step to restoring normal local network operation.
Unlike wireless interference, which is often temporary, cable or driver issues require a systemic approach to diagnosis. Ignoring the fact that your connection is slow LAN This can lead to constant connection interruptions when transferring large files or unstable online services. In this article, we'll examine all possible causes in detail and provide a step-by-step solution.
Physical limitations and the state of the cable infrastructure
The first thing to rule out when diagnosing is physical defects in the cable itself or connectors. Old or damaged twisted pair cable may only operate at 100 Mbps, even if your router and ISP support 1 Gbps. This occurs if only four of the eight wires in the cable are in use, which is typical for the standard. 100BASE-TX.
Often the problem lies in poor quality crimping of connectors RJ-45If the contacts are corroded or the wires are damaged, the network card automatically reduces the connection speed to maintain link stability. This is difficult to determine visually, so the best solution is to replace the patch cord with a known-good cable of at least category Cat5e.
Cable length also plays a role: beyond 100 meters, the signal weakens, and equipment switches to lower speeds or loses connection. If you're using a long cable running through your entire home, make sure it meets standards and is free of twists.
⚠️ Attention: If the router's port LED is orange or yellow instead of green, this often indicates that the router is operating in 10/100 Mbps mode, not 1 Gbps. First, check the cable's physical integrity.
Don't forget about your router's ports either. On some older models, the ports WAN And LAN They may have different throughput. Make sure you're connected to a gigabit port, if your device model has one.
Problems with PC network card drivers
The software that controls your network adapter often becomes a bottleneck. Outdated drivers may not work correctly with modern protocols or may not support power-saving modes, which artificially limits speed. The operating system may not be able to see the full capabilities of your network controller.
You can check the current connection status through the Device Manager or the command line. Enter the command netsh interface show interfaceto see the adapter status. If the speed is listed as 100 Mbps with a gigabit plan, the problem is clearly with the link between the card and the router.
Automatic Windows driver installation often selects a universal, but not optimal, option. It is recommended to download the latest software from the official website of the motherboard or network adapter manufacturer (e.g., Realtek, Intel, Killer). After installation, be sure to reboot the system.
How to check negotiated speed in Windows
Open PowerShell and enter the command: Get-NetAdapter | Select-Object Name, Status, LinkSpeed. This will show the actual connection speed for each adapter.
It is also worth checking the parameter in the adapter settings Speed & DuplexIt should be in the mode Auto NegotiationForcing a value may cause conflicts if the router does not support the selected mode.
Router settings and traffic prioritization
Modern routers have complex traffic distribution algorithms that can unintentionally limit wired ports. Function QoS (Quality of Service) Often configured by default to prioritize wireless devices or certain types of traffic, such as streaming or gaming.
In the administrator interface, accessible at 192.168.0.1 or 192.168.1.1, check the sections related to bandwidth management. It's possible that the LAN port has a speed limit (Bandwidth Control) that was previously set and forgotten.
- 📶 Frequency range: Make sure your Wi-Fi is running at 5GHz, which can theoretically outperform older Fast Ethernet (100Mbps), but shouldn't outperform Gigabit Ethernet.
- ⚙️ Firmware: Outdated router software may contain bugs that affect the operation of the switch.
- 🔌 CPU Load: When heavy functions are enabled (torrents, VPN on the router), the processor may not be able to handle routing, and the difference in speed will become more noticeable.
Resetting your router to factory settings can often help eliminate software configuration errors. However, before doing so, be sure to back up your current settings if they are complex or customized.
The impact of antivirus and firewall
Third-party antivirus software and firewalls can scan all incoming and outgoing traffic in real time. This places additional strain on the computer's processor and introduces delays, which show up as a slowdown in speed tests. This is especially noticeable on fast connection lines.
Try temporarily disabling network protection in your antivirus and running the speed test again. If the results increase to the expected values, you should add your browser or testing program to the exceptions list.
The built-in Windows firewall could also be the cause. Check your incoming and outgoing connection rules. Sometimes, after a system update, the rules get messed up, and traffic starts being filtered excessively.
⚠️ Attention: Don't leave your computer without antivirus protection for long periods of time. Test only on trusted resources and re-enable protection immediately.
Feature Comparison: Ethernet vs. WiFi
To assess the situation objectively, it's important to understand the theoretical limits of these technologies. The table below provides comparative specifications to help you understand what's acceptable for your equipment.
| Parameter | Ethernet (Cat5e/Cat6) | Wi-Fi 5 (AC) | Wi-Fi 6 (AX) |
|---|---|---|---|
| Max. speed (theoret.) | 1000 Mbps (1 Gbps) | 866 Mbps | 1200+ Mbps |
| Ping stability | High (1-3 ms) | Medium (5-15 ms) | Medium (4-10 ms) |
| The influence of interference | Minimum | High | Average |
| Full duplex | Yes (at the same time) | No (in turn) | Partially |
As the table shows, Wi-Fi 6 can approach the performance of a gigabit cable under ideal conditions, but only in the absence of interference and close proximity to the client. However, actual speeds will always be lower than theoretical values due to protocol overhead.
If your internet plan exceeds 100 Mbps and your cable is old (Cat5 without markings), you won't be able to get the high speed. In this case, replacing the cable is the only solution.
Diagnostics and troubleshooting methods
To accurately identify the problem, use a comprehensive approach. Start with a simple test: connect another computer or laptop using the same cable. If the speed is slow everywhere, the problem is with the cable or router. If the problem only occurs on one computer, look for the cause in its settings.
Use the command line to reset network settings. The command netsh int ip reset Resets the TCP/IP stack to factory defaults. A reboot is required after performing this.
☑️ Diagnostic checklist
It's also worth checking that no background downloads are running. Torrents, Steam updates, or cloud syncing services can consume your entire bandwidth, creating the illusion of low speed during testing.
How to measure internet speed correctly?
To obtain reliable data, close all programs using the network. Use a wired connection for testing to eliminate the possibility of interference from the radio channel. It's best to use services that offer a choice of servers closest to your location.
Can a router cut speed?
Yes, weaker router models may not be able to handle higher speeds (for example, above 300-400 Mbps) due to low processor or NAT table performance. In this case, the only solution is to upgrade to more powerful equipment.
Does cable length affect speed?
For twisted pair cable, the critical length is considered to be 100 meters. At distances of up to 50-70 meters, significant speed loss is excluded. Problems arise if the cable is located near powerful sources of electromagnetic radiation.
If none of these methods help, the problem may lie in a hardware fault with the network card or router port. In this case, it's advisable to contact a service center or replace the network adapter with an external USB card.