Why is my internet so slow?
Slow internet usually results from a problem somewhere between your device and the online service you are trying to reach. Weak Wi-Fi, network congestion, background downloads, outdated equipment, device problems and ISP service issues are common causes.
Your internet connection has several components. Your device connects to a router through Wi-Fi or Ethernet, and the router forwards traffic through your internet provider's network to remote services. A problem at any point along this path can affect browsing, downloads, streaming, gaming or video calls.
A speed test helps measure connection performance, but download speed alone does not explain every slowdown. Latency, jitter, packet loss and performance under load also affect how responsive an internet connection feels. Cloudflare's Aggregated Internet Measurement framework evaluates all six of these metrics: download, upload, latency, loaded latency, jitter and packet loss (Cloudflare, Aggregated Internet Measurement).
How to diagnose a slow internet connection
Use a consistent testing sequence before changing router settings or buying new equipment. The following eight steps help narrow down whether the problem comes from one device, Wi-Fi, shared network activity, equipment or your provider.
1. Check whether one device or all devices are slow
Connect another phone, laptop or computer to the same network and compare its performance. Use the same website or speed-test service where possible.
- One device is slow: Check its background applications, browser, VPN, network adapter and connection settings.
- Several devices are slow: Investigate the router, modem, household network activity or internet service.
A comparison across devices helps separate an individual device problem from a problem shared by the network. Microsoft also recommends testing another computer when investigating Ethernet connection problems (Microsoft Support: Fix Ethernet connection problems in Windows).
2. Compare Wi-Fi with Ethernet
Connect a computer directly to the main router using an Ethernet cable, then run the same speed test you used over Wi-Fi. Avoid connecting through a wireless extender for this comparison because the connection between the extender and main router can still use Wi-Fi.
Compare the results:
- Ethernet is fast but Wi-Fi is slow: Investigate wireless signal strength, distance, interference or router placement.
- Both connections are slow: Check equipment, network activity, the provider connection and the test conditions.
- Both are fast but one application is slow: Investigate that application, its server, DNS resolution or network route.
Check that the Ethernet cable is firmly connected at both ends. Test another cable or router port when available. Microsoft recommends these checks as part of its Ethernet troubleshooting guidance (Microsoft Support).
3. Test near the router and in the problem area
Run a Wi-Fi speed test near the router, then repeat it in the room where the slowdown occurs. Use the same device and testing service for both measurements.
A large performance difference between locations points towards a wireless coverage problem. Walls, floors, building materials, distance and nearby wireless equipment all affect Wi-Fi performance.
Microsoft recommends running several tests in different parts of the home, recording the results and testing again after making changes. Its Wi-Fi guidance also explains the differences between the 2.4 GHz, 5 GHz and 6 GHz bands (Microsoft Support: Wi-Fi and your home layout).
4. Compare different websites and applications
Open several unrelated websites and applications. Check whether the slowdown affects everything or only one destination.
If one website is slow while other services work normally, the problem does not automatically indicate a broadband fault. The website's server, its content-delivery network, DNS resolution or the network route to that service can affect loading time.
DNS, or Domain Name System, translates domain names into network addresses. Microsoft documents DNS problems caused by incorrect client settings, unreachable DNS servers and intermediate network devices (Microsoft Learn: Troubleshoot DNS client name resolution issues).
5. Check download, upload and latency
Run an internet speed test and record the available measurements.
| Measurement | What it tells you |
|---|---|
| Download speed | How quickly your device receives data |
| Upload speed | How quickly your device sends data |
| Ping or latency | How long a response takes to travel to a test destination and return |
| Jitter | How much packet delay varies |
| Loaded latency | How response delay changes while network traffic is active |
| Packet loss | Whether packets fail to reach their intended destination under the test method |
Use the internet speed test, download test, upload test and ping test to investigate the relevant measurements.
A fast download result does not guarantee responsive gaming or uninterrupted video calls. Cloudflare's measurement framework treats throughput and responsiveness as separate performance characteristics (Cloudflare, Aggregated Internet Measurement).
The measurement method matters too. Browser-based HTTP request failures are not automatically equivalent to network-layer ICMP or UDP packet loss. Check the methodology of any packet-loss tool before interpreting its result.
6. Compare results at different times
Repeat the same tests when the connection is working normally and when the slowdown occurs. Record the time, device, connection type, download speed, upload speed and latency.
If performance consistently drops during a busy period, investigate household activity and provider-side capacity. A single evening slowdown does not prove ISP throttling. Other devices, streaming, large downloads and local wireless interference can also contribute.
Ofcom recommends testing more than once because broadband speed can vary by day and time. It also explains that speed is not the only factor affecting services such as video calls and online gaming (Ofcom broadband and Wi-Fi help).
7. Check background network activity
Look for large downloads, cloud backups, software updates, game downloads and streaming sessions on connected devices.
Pause one high-bandwidth activity and repeat the test. If performance improves, competing network traffic was contributing to the slowdown.
The number of connected devices alone does not establish that a network is overloaded. Actual activity matters. Google explains that simultaneous high-bandwidth tasks, including video streaming and large downloads, compete for the available connection capacity (Google Nest Help: Troubleshoot slow internet).
8. Change one variable and retest
Record your original result, make one relevant change and repeat the test under similar conditions.
For example, move the router to a more open location, pause a large download or replace a suspect Ethernet cable. Do not change several router settings at once because you will not know which change affected the result.
This controlled comparison creates a more useful troubleshooting record than repeatedly restarting equipment without checking what changed.
What causes slow internet?
The cause of slow internet depends on which part of the connection is limiting performance. These are the main possibilities.
Weak Wi-Fi signal and wireless interference
Wi-Fi performance changes with distance, obstacles, interference, router placement and device capabilities.
Consumer Wi-Fi equipment can use the 2.4 GHz, 5 GHz and 6 GHz frequency bands, but not every router or device supports all three.
- 2.4 GHz: Provides longer range and better obstacle penetration, but it has fewer non-overlapping channels and more potential interference.
- 5 GHz: Generally offers higher throughput and more non-overlapping channels, but has shorter range than 2.4 GHz.
- 6 GHz: Requires compatible Wi-Fi 6E equipment and devices, and performs best when the device is close to the router.
These are trade-offs, not a universal ranking. A strong 2.4 GHz connection can outperform a weak 5 GHz connection through several walls. See Microsoft's Wi-Fi band and home-layout guidance.
Too many devices and background downloads
Connected devices share the available household network capacity. A television streaming video, a laptop downloading files and a console downloading a game can compete for bandwidth.
Check which devices are active before upgrading your plan. Temporarily pause large transfers and compare performance again.
Router, modem, ONT and Ethernet problems
A slow connection can result from faulty cables, unsuitable Ethernet ports, equipment configuration or an access device that cannot handle the service rate.
For fiber broadband, the ONT connects the customer-side equipment to the provider's fiber access network. A separate router then manages the local network. Equipment arrangements differ between providers.
Check power, status lights, cable connections and port ratings. Google also explains that the slowest component in a network path can limit the overall connection speed (Google Nest Help).
ISP congestion, outages and service limitations
Your provider supplies the internet connection reaching your home. Provider maintenance, service faults, shared network demand and the speed limits of your plan can affect multiple devices simultaneously.
Check the provider's service-status page or application. Ask whether there is an outage or known network problem before assuming the router needs replacing.
Device, browser and software problems
An older network adapter, outdated driver, background application, VPN or browser extension can affect one device without slowing every device on the network.
Close unnecessary applications and compare another browser or device. On Windows, check the network adapter and connection status before attempting advanced network resets.
DNS and remote website problems
DNS problems affect the translation of domain names into IP addresses. An unreachable DNS server can cause a lookup to time out, delaying access to a website even when the broadband connection itself is working.
A remote website or application can also be slow independently of your local internet connection. Compare several services before changing DNS settings or blaming the provider.
High latency and network congestion under load
Internet speed and responsiveness are different characteristics. A connection can deliver high download throughput while experiencing delayed responses during uploads or downloads.
This problem is related to packet queues and congestion management. The IETF's July 2015 RFC 7567, Active Queue Management Recommendations, discusses ways network devices manage packet queues to preserve internet performance.
The history of TCP congestion control provides further context. The September 2009 RFC 5681 documented TCP mechanisms including slow start, congestion avoidance, fast retransmit and fast recovery. The August 2023 RFC 9438 updated RFC 5681's specification of TCP CUBIC. These standards demonstrate that congestion management is a fundamental part of network performance, not simply a question of advertised download speed.
For a deeper explanation of latency under load, read bufferbloat explained.
Why did my internet suddenly become slow?
A sudden slowdown is a change in connection performance compared with your previous results. Recent software updates, new devices, router changes, damaged cables, background downloads and provider outages are useful starting points for investigation.
Think about what changed shortly before the problem began. Check the router and fiber equipment status, disconnect recently added devices and compare another device on the same connection.
If the problem started after moving the router or changing the home network, temporarily restore the earlier setup and test again. Ofcom recommends checking recent changes, household activity and wider outages when diagnosing broadband problems (Ofcom broadband troubleshooting).
Why does my internet slow down at night?
Night-time slowdowns can result from greater household usage or congestion elsewhere in the provider network. Streaming, gaming, automatic backups and downloads can increase demand at the same time.
Compare the same wired and wireless tests during quieter hours and during the slowdown. Repeat these measurements on different days before treating the pattern as evidence of a provider fault.
Why does my internet feel slow even after a good speed test?
A speed test measures performance to a particular testing service under specific conditions. It does not measure every website, application, network route or device process.
Download and upload results describe throughput. Ping describes round-trip response delay. Jitter describes variation in delay, while loaded latency shows how responsiveness changes during active network traffic.
If browsing remains slow after a good speed test, compare unrelated websites, check another device and investigate DNS resolution. If performance becomes poor during heavy uploads or downloads, examine latency under load with the bufferbloat test.
If you investigate packet loss, check what the test actually measures. A failed browser HTTP request does not automatically establish ICMP or UDP packet loss. For a deeper explanation, see packet loss troubleshooting.
Is your router, Wi-Fi, device or ISP causing slow internet?
Use your comparison results to identify the next area to investigate. These results are diagnostic clues, not automatic proof of responsibility.
| Your test result | What it suggests | What to check next |
|---|---|---|
| One device is slow | Device-specific issue | Applications, browser, adapter and network settings |
| All devices are slow | Shared network or provider issue | Router, modem, ONT, active traffic and provider status |
| Wi-Fi is slow but Ethernet is normal | Wireless connection issue | Distance, walls, interference and router placement |
| Wi-Fi and Ethernet are both slow | Shared equipment or upstream issue | Cables, router, access equipment and ISP service |
| Only one website is slow | Website, DNS or route-specific issue | Other services, browser and DNS resolution |
| Internet slows down at night | Time-dependent network demand | Household activity and repeat tests |
| Latency rises during uploads | Latency-under-load problem | Background transfers and bufferbloat |
When a Windows computer is affected, Microsoft's Ethernet troubleshooting guide also explains how a second-device comparison helps distinguish a computer problem from router or provider problems.
How to fix slow internet based on your test results
Choose the fix that matches the problem you identified. Start with reversible changes and retest before attempting advanced configuration.
Restart your modem and router correctly
Restarting networking equipment can restore a temporary connection problem. It does not erase the router's saved configuration.
For separate modem and router devices, Microsoft's general restart procedure is:
- Unplug the router and modem from power.
- Wait at least 30 seconds.
- Reconnect the modem and wait for its connection lights to settle.
- Reconnect the router and allow it to finish starting.
- Reconnect your device and test the connection again.
The correct sequence depends on the equipment. Follow your provider's instructions, especially when a separate fiber ONT is installed. See Microsoft's Ethernet connection troubleshooting instructions.
Improve Wi-Fi signal and router placement
Place the router in a central, open location rather than behind furniture or inside a closed cabinet. Reduce physical obstructions and compare performance in the rooms where you use the internet.
A mesh system or additional access point can help with coverage, but its placement and connection to the main router also affect performance. Google recommends checking the distance and placement of Wi-Fi points when troubleshooting slow connections (Google Nest Help).
Stop unnecessary background network activity
Pause large downloads, cloud backups and software updates temporarily. Check whether another connected device is streaming or transferring large files.
Repeat the speed test after reducing activity. If performance improves, investigate which task is consuming the available capacity.
Check Ethernet cables and network equipment
Make sure Ethernet cables are securely connected and use another known-working cable if the current one appears damaged. Check the connection ports on the router and computer.
A wired connection can still be limited by an older network adapter, port or other device in the network path. Google recommends checking cable and equipment ratings when Ethernet connections limit speed.
Update network software and drivers when needed
Install relevant operating-system, router and network-adapter updates through the manufacturer or operating-system provider.
Avoid uninstalling network drivers or resetting network settings as a first response. Windows network reset removes installed network adapters and their settings, and it can require VPN or virtual-network software to be configured again. Microsoft recommends network reset as a last troubleshooting step (Microsoft Ethernet guidance).
Contact your ISP when the problem is outside your home network
Contact the provider when multiple devices experience persistent slowdowns, wired tests remain poor, or the provider reports an outage or service fault.
Give the support team your test results and explain what you have already checked. This helps them investigate the service instead of asking you to repeat basic steps.
When should you contact your internet provider?
Contact your internet provider when repeated tests show that the problem affects multiple devices and remains present after basic local checks.
Prepare the following information:
- The date and time the slowdown began.
- Whether the problem is constant or intermittent.
- Download and upload measurements.
- Ping and loaded-latency results, if available.
- Whether you tested through Wi-Fi or Ethernet.
- Which devices and applications are affected.
- Whether restarting equipment or pausing background activity changed the result.
- Any outage messages or unusual equipment status lights.
Ask whether the provider has a known outage, service-line fault, equipment problem or capacity issue. Keep the test record so you can compare performance after the provider investigates.
Ofcom's consumer guidance recommends telling a provider when a problem began, whether it is constant or intermittent, and which checks and fixes have already been attempted. This is UK-specific consumer guidance, but keeping the same evidence is useful when contacting providers in other markets (Ofcom).
Should you upgrade your internet plan?
Upgrade your internet plan only after checking the local network, equipment and service performance. A higher-capacity plan helps when household demand consistently exceeds the capacity of the existing service.
It does not fix weak Wi-Fi, faulty cables, device problems or a slow remote website. Compare your household's simultaneous activities and required download and upload performance before choosing a plan.
For a household-level assessment, read how much internet speed do I need?.