Why Is My Internet Slow? 12 Common Causes and Fixes

Slow internet is frustrating, but the cause is usually one of a handful of common problems. Work through these steps in order. Each one rules out a whole group of causes, so you will find the culprit faster than by trying random fixes.

Step 1: measure the problem

Run a speed test and note four numbers: download, upload, latency and latency under load. Then work out which kind of “slow” you have:

• Low download speed: videos buffer and downloads crawl.
• Low upload speed: video calls freeze for the other person, and backups take forever.
• High latency or jitter: pages take a moment to start loading, and games lag.
• High latency under load: everything lags when someone else is downloading. This is bufferbloat.

Step 2: find where the problem is

Test with a computer connected by cable directly to your router.

• Cable result good, Wi-Fi poor: the problem is your Wi-Fi. Go to causes 1–4.
• Cable result poor too: the problem is your router, modem or internet connection. Go to causes 5–12.

Wi-Fi and device causes

1. Distance and walls. Wi-Fi weakens quickly through walls, floors, mirrors and metal. Move closer to the router, or put the router in a central, raised, open position.
2. The 2.4 GHz band. It reaches further but is slower and more crowded. Use 5 GHz (or 6 GHz on Wi-Fi 6E/7 equipment) when you are near the router.
3. Interference and neighbours. Many nearby networks on the same channel compete for airtime. Let the router choose a channel automatically, or choose a less crowded one.
4. An old or busy device. Older phones and laptops have slower Wi-Fi chips. Restart the device, update it and close bandwidth-hungry apps. Compare the result with a newer device.

Router and connection causes

5. The router needs a restart. Routers run for months without a break, and a restart clears memory problems. Unplug for 30 seconds, then reconnect and wait a few minutes.
6. Outdated firmware. Check your router’s admin page or app for updates. They often fix performance and security problems.
7. Bufferbloat. If latency jumps when the line is busy, turn on Smart Queue Management (SQM) or “adaptive QoS” if your router supports it.
8. Background traffic. Cloud backups, game downloads, security cameras and software updates can quietly take most of your bandwidth. Check your router’s device list.
9. Loose or damaged cables. Check the cables between the wall socket, modem and router. Replace any that are kinked or damaged.
10. Peak-time congestion. If speed drops mainly in the evening, your provider’s local network may be overloaded. Keep a record of tests at different times.
11. Your plan. Check what your plan actually includes, especially the upload speed. You may simply have outgrown it. See how much speed you need.
12. An outage or line fault. Check your provider’s service-status page or app. Line faults often show up as slow speeds plus packet loss.

When to contact your provider

Contact them if, on a wired connection, with other devices paused:

• download or upload is consistently far below your plan,
• latency or packet loss is high even when the line is quiet, or
• the connection drops out regularly.

Give them evidence: several results taken at different times, with dates. SpeedCheckWeb can export your test history as a CSV file. Your provider may also ask you to use their own test, because it measures to a server inside their network.

Quick fixes that often help

• Restart the router and modem.
• Use a cable for computers and consoles that stay in one place.
• Move the router somewhere central and open.
• Turn on SQM or adaptive QoS if available.
• Pause cloud backups during calls and gaming.

Run a speed test before and after each change to see what really helped.

Sources

1. FCC – Broadband speed guide
2. Bufferbloat.net – project overview and fixes

Figures from third parties can change; we review guides regularly. See our editorial policy.