Slow Wi-Fi: Why is internet speed through a router slower than via cable, and how to fix it?

Have you connected your laptop or smartphone to Wi-Fi, but pages take forever to load, videos are slow, and online games are laggy—even though everything works perfectly over a cable? This problem is familiar to millions of users, and often its causes lie not with your ISP, but with your home network settings. Internet speed via Wi-Fi The connection speed can drop by 2–10 times compared to a wired connection, and several factors are to blame: from outdated equipment to interference from neighboring routers.

In this article we will look at All possible reasons for slow Wi-Fi — from the obvious (like an improperly positioned router) to the more subtle (like bandwidth congestion or DNS issues). You'll learn how to diagnose the problem yourself, which settings to check first, and when it's time to consider replacing your equipment. Finally, you'll find a quick checklist and an FAQ with answers to the most frequently asked questions.

1. Router issues: outdated firmware or hardware limitations

The first thing you need to check is yourself routerEven if it distributes internet properly, its internal settings or technical specifications may slow down the speed. For example, budget routers (like TP-Link TL-WR840N or D-Link DIR-300) are physically unable to provide a higher speed 100–150 Mbps even at the rate of 500 MbpsThis is due to processor and RAM limitations.

Another common reason is - outdated firmwareManufacturers regularly release updates that optimize Wi-Fi performance, fix vulnerabilities, and add support for new standards (for example, Wi-Fi 6). If your router hasn't been updated in years, it may run 30-50% slower than it could.

• 🔄 How to update firmware: Go to the router's web interface (usually at 192.168.0.1 or 192.168.1.1), find the section System Tools → Software Update and follow the instructions. Download the firmware ONLY from the manufacturer's official website!
• 📉 Hardware limitations: If your router is older than 5 years, it most likely does not support modern standards. 802.11ac or 802.11axIn this case, even flashing the firmware won't help—you'll need to replace the device.
• ⚡ Overheat: Routers running 24/7 can overheat, especially if they're stored in a closed cabinet. This leads to automatic power throttling and a drop in speed.

⚠️ Attention: Some routers (for example, models ASUS RT-N12 or Zyxel Keenetic Lite) After updating the firmware, the settings may be reset to factory defaults. Before updating, save the configuration to a file using the section Administration → Save/Restore.

2. Incorrect Wi-Fi settings: channel, bandwidth and connection standard

Even the most powerful router will slow down if it Wi-Fi settings Not optimized. The main parameters affecting speed:

• 📶 Wi-Fi channel: In apartment buildings, routers in neighboring apartments often operate on the same channel (for example, 6th or 11th in the range 2.4 GHz), creating interference. It's like a traffic jam—the more cars (devices), the slower the traffic (speed).
• 📊 Channel width: You can choose in the settings 20 MHz, 40 MHz or 80 MHz (For 5 GHz). The wider the channel, the higher the potential speed, but also the more interference from other devices.
• 🔗 Wi-Fi standard: If an outdated standard is selected in the router settings 802.11b/g, the maximum speed will be limited 54 Mbps, even if your tariff is on 300 Mbps.

How to check and change settings:

1. Log in to your router's web interface (logins and passwords are usually located on a sticker on the back of the device).
2. Find the section Wireless network (Wi-Fi) or Wireless Settings.
3. Install:
   • Standard: 802.11n/ac (For 2.4 GHz) or 802.11ac/ax (For 5 GHz).
   • Channel width: 40 MHz For 2.4 GHz or 80 MHz For 5 GHz.
   • Channel: Auto or select the least loaded one manually (use apps like Wi-Fi Analyzer for Android).

3. Interference from other devices and networks

Your Wi-Fi doesn't operate in a vacuum: its speed is affected by neighboring networks, household appliances and even walls. In the range 2.4 GHz (which is used by most routers) a huge number of devices work:

• 📱 Smartphones and tablets neighboring apartments.
• 🎮 Game consoles (For example, PlayStation or Xbox).
• 🔌 Household appliances: microwave ovens, baby monitors, wireless headphones, CCTV cameras.
• 🚗 Smart devices: light bulbs Xiaomi, sockets TP-Link Tapo, sensors Aqara.

As a result, your router's signal encounters interference, and speed drops. This is especially noticeable in the evening, when all your neighbors are actively using the internet.

How to reduce the impact of interference:

• 🔄 Switch to range 5 GHz (If your router and devices support it). There's less interference, but the signal doesn't penetrate walls as well.
• 📡 Use Wi-Fi analysis apps (e.g. NetSpot or Wi-Fi Analyzer) to find the least loaded channel.
• 🏠 Move the router away from the microwave, refrigerator, and other electrical appliances.
• 🛡️ If you have a dual-band router, separate the networks: for example, MyWiFi_2G And MyWiFi_5G, and connect devices to the less crowded range manually.

⚠️ Attention: In the range 5 GHz some channels (100–140) may require support DFS (Dynamic Frequency Selection). If your router or device doesn't support DFS, these channels will be unavailable, and the router may automatically switch to congested ones.

4. Provider restrictions: tariff, DNS, throttling

Sometimes the problem isn't with your hardware, but with providerHere are three key points to check:

1. Tariff plan: Make sure your plan actually provides the speed it claims. For example, if you have a plan for 100 Mbps, then you are unlikely to get more over Wi-Fi 80–90 Mbps (due to protocol overhead). You can check the actual speed on the websites Speedtest.net or Yandex.Internetometer.
2. DNS servers: Providers often use their own DNS, which can be slow or block some websites. Replacing with a public DNS (for example, 8.8.8.8 from Google or 1.1.1.1 (from Cloudflare) can speed up page loading times by 10–30%.
3. Throttling (artificial limitation): Some providers reduce speeds for certain types of traffic (for example, torrents or video streams). This can be difficult to diagnose, but if the speed drops only on specific websites or services, this could be the cause.

How to check your provider's restrictions:

1. Connect your computer directly to the provider's cable (bypassing the router) and run a speed test. If the speed via cable is also low, the problem is with your ISP.
2. Call support and check if there are any temporary restrictions in effect (for example, due to exceeding the traffic limit).
3. Try changing the DNS in your router or device settings:

   On Windows: Control Panel → Network and Internet → Network and Sharing Center → Change adapter settings → Properties → IPv4 → Use the following DNS addresses

⚠️ Attention: If you use VPNThis can also significantly reduce speed. Some VPN services limit bandwidth or route traffic through overloaded servers. Try disabling the VPN and running the speed test again.

5. Client devices: old adapters, drivers, power saving settings

Even if the router is configured perfectly, a device that connects to Wi-Fi, may be a bottleneck. Here are the most common problems:

• 🖥️ Outdated Wi-Fi adapter: Laptops older than 5-7 years often come with adapters that only support Wi-Fi 4 (802.11n) at maximum speed 150–300 Mbps. For example, an adapter Intel Centrino Wireless-N 1000 physically incapable of working faster.
• 🔧 Outdated drivers: Wi-Fi adapter drivers may contain errors or fail to support modern standards. For example, on Windows 10/11, drivers are often updated automatically, but not always to the latest version.
• 🔋 Power saving mode: Windows laptops may have a power saving mode enabled for the Wi-Fi adapter by default, which reduces its performance.

How to check and fix:

1. Find out the model of your Wi-Fi adapter:

   On Windows: Win + R → enter msinfo32 → Components → Network → Adapter

   On macOS: About This Mac → System Report → Network.

2. Update your drivers:
   • For Windows: Download the latest version from the manufacturer's website (e.g. Intel, Qualcomm Atheros or Realtek).
   • For macOS: Driver updates are delivered with system updates.

On Windows: Device Manager → Network Adapters → [your adapter] → Properties → Power Management → Uncheck "Allow the computer to turn off this device..."

Find out the adapter model

Check supported standards (Wi-Fi 4/5/6)

Update drivers to the latest version

Disable power saving mode

Test speed on another device-->

6. Physical obstacles and router location

Wi-Fi speed depends heavily on router location and the materials the signal passes through. Here's how various obstacles affect speed:

• 🧱 Walls made of concrete or brick: can reduce speed by 50–70% already at a distance of 10 meters from the router.
• 🪞 Mirrors and metal surfaces: reflect the signal, creating "dead zones".
• 🚪 Interior doors: especially metal ones, they weaken the signal by 10–20%.
• 🌿 Houseplants and aquariums: Water absorbs radio waves well, so large aquariums can block the signal.

Optimal router placement:

• 📍 Install a router in the center of the apartment, and not in the corner.
• 📏 Raise it to the top 1–1.5 meters (for example, on a shelf or table).
• 🚫 Keep away from metal objects, microwaves and other appliances.
• 🔄 If the apartment is large, consider buying Mesh systems (For example, TP-Link Deco or ASUS ZenWiFi) or repeater (signal repeater).

If moving your router is not possible, try using directional antennas (For example, TP-Link TL-ANT2408CL) or replace standard antennas with more powerful ones.

7. Network congestion: too many connected devices

Every device connected to your Wi-Fi, consumes some of the bandwidthIf the following devices are simultaneously connected to the router:

• 📺 Smart TV (especially if you are streaming 4K video).
• 🎮 Game consoles (online games require a stable ping).
• 📱 Smartphones and tablets (especially if updates are being downloaded).
• 🖥️ Computers with torrents or cloud synchronizations.
• 💡 Smart devices (light bulbs, cameras, sockets).

...then even with the tariff on 500 Mbps the speed on each device may drop to 10–20 Mbps.

How to reduce network load:

• 🔌 Disable unnecessary devices from Wi-Fi (for example, old smartphones or smart light bulbs that are no longer in use).
• 🕒 Set up a schedule for updates and backups (for example, at night).
• 🎯 Prioritize traffic through QoS (Quality of Service) in the router settings. For example, you can allocate maximum speed for Smart TV or a game console.
• 🔄 Separate devices by range: for example, connect smart light bulbs to 2.4 GHz, and the laptop and TV - to 5 GHz.

⚠️ Attention: Some smart devices (such as cameras) Xiaomi or light bulbs Philips Hue) can generate hundreds of small requests per second, overloading the router. If the speed drops when they're connected, try connecting them to a separate guest network.

8. External attacks and unauthorized connections

If your Wi-Fi is not secured or the password is too simple, someone can connect to it. third-party users (Neighbors, passersby). This not only reduces speed but also creates security risks. Also, some viruses or botnets can use your connection for DDoS attacks or cryptocurrency mining.

How to check and protect yourself:

1. View the list of connected devices in the router's web interface (section Wireless Network → Client List or DHCP Clients ListIf you see unfamiliar devices, change your Wi-Fi password.
2. Set a strong password (at least 12 characters, including numbers and special characters). The optimal encryption standard is WPA2-PSK or WPA3.
3. Disable the feature WPS (Wi-Fi Protected Setup) - it is vulnerable to hacking.
4. Turn on MAC address filtering (although this is not a panacea, since MAC can be counterfeited).

If you suspect that your router is infected with a virus (for example, the speed drops even without connected devices), perform a factory reset (button Reset on the back panel) and set it up again.

FAQ: Answers to Frequently Asked Questions