Quick answer
First measure speed on a wired connection, then on WiFi, to see if the problem is with your provider or your network. Then disconnect unnecessary devices and programs that use bandwidth, check the router and DNS, and update drivers and firmware if needed. If the measured speed consistently deviates from the contracted speed, contact your provider with the measurement results.
How to recognize the problem
- Pages take several seconds to load, and video stutters even at low resolution
- File downloads are much slower than before
- Speed is good in the morning but noticeably drops in the evening
- Multiple devices on the network simultaneously slow everything down
- WiFi works well in the same room but is slow in other parts of the apartment
Most common causes
Difference between contracted and actual speed
Providers advertise maximum speed that is rarely achieved at all times. A deviation of 10 to 20 percent on a wired connection is common.
WiFi and distance from the router
Walls, floors, and other devices on the same frequency reduce wireless connection speed. WiFi almost never delivers full throughput like a LAN cable.
Devices and programs that consume bandwidth
System updates, cloud backups, 4K streaming, and torrent clients can take up all the bandwidth. The same applies to guests connected to your network.
Outdated router or poor settings
Older routers do not support faster standards, and a router that hasn't been restarted for a long time can work unstable. Sometimes changing the DNS server helps too.
Slow computer, not slow internet
A browser with many extensions, malware, or a full disk can create the impression that the connection is slow, even though throughput is fine.
Step-by-step fix
- 1
Measure speed on a wired connection
Connect your computer directly to the router with a LAN cable and turn off WiFi. Open a speed test in your browser and run the test several times, at different times of day. Note the download, upload, and latency (ping) results.
- 2
Measure speed over WiFi
Repeat the same measurement with your phone or laptop on WiFi, first in the same room as the router, then in another room. If the difference is large, the problem is coverage, not the provider.
- 3
Compare with the contracted speed
Check your contract or provider portal for the speed you are paying for. If the wired measurement consistently shows significantly less than the contracted speed, the cause is most likely outside your network.
- 4
Disconnect unnecessary devices and programs
Temporarily disconnect other devices from the network and close programs that download or share files. Also check if any phone is backing up photos to the cloud. Then measure speed again.
- 5
Restart the router and modem
Unplug the router and modem from power, wait 30 seconds, and plug them back in. Wait for all lights to stabilize, which usually takes two to three minutes, then repeat the measurement.
- 6
Check who is connected to the network
Open the router administration in your browser, usually at
192.168.1.1or192.168.0.1, and log in with the credentials from the label on the router. In the client list, look for unknown devices, block them, and change the WiFi password. Keep in mind that all devices will be disconnected from the network, so you will need to reconnect them. - 7
Change the DNS server
In Windows, go to
Settings > Network & Internet > Wi-Fi(or Ethernet), open the properties of the active connection, and find the DNS server settings. Enter public DNS addresses, for example1.1.1.1and8.8.8.8. This does not increase throughput but often speeds up page loading. - 8
Update the system, drivers, and firmware
Install all Windows and browser updates, and in Device Manager check if there is a newer driver for the network adapter. In the router administration, look for a firmware update option and apply it if available, but do not interrupt power during the update.
- 9
Check the computer for malware
Run a full scan with the built-in antivirus and review browser extensions. Remove ones you do not use, as some can inject ads and consume bandwidth.
If nothing helped
If the wired measurement is consistently below the contracted speed, call your provider and provide the exact measurement results with date and time. Before that, check that the cable is not damaged and that the modem is working properly. In an office with multiple employees, consider a router that supports traffic prioritization, so video calls have priority over downloads. If speed changes during the day, it is often due to provider network load and is worth discussing with support.
How to prevent it
- Restart the router occasionally, for example once a month
- Keep the router in an open place, away from walls and the microwave oven
- Regularly update the router firmware and operating system
- Do not share the WiFi password widely and check the list of connected devices
When to call a professional
If you have disconnected all devices, restarted the equipment, and measured speed with a cable, and the deviation still exists, it is better to contact your provider or IT support than to change router settings yourself. A professional check quickly determines whether the problem is in the equipment, configuration, or the line itself.
IT infrastructure maintenance · Servers, networks, backup, security and helpdeskFAQ
Is the speed shown by the test reliable?
Yes, if measured on a wired connection and without other active devices. WiFi measurements are useful for assessing coverage but do not show the actual throughput reaching the router.
Why is my internet slow only in the evening?
In the evening, more users use the provider's network, so speed is shared. If this repeats every day at the same time, it is likely congestion at the provider, not your equipment.
Does changing DNS speed up the internet?
It does not increase throughput but can speed up page loading because addresses are resolved faster. If the problem is downloading large files, DNS will not help.