Why Is My Internet So Slow? Causes and Fixes
Slow internet is usually caused by one of three things: your WiFi (distance, walls, interference), your devices (background downloads, an old router) or the network (evening congestion, line faults, or national problems such as a submarine cable cut). A wired speed test tells you which one it is.
How do I find the cause in two minutes?
| Test | Result | Meaning |
|---|---|---|
| Wired test vs package | Close to package | Line is fine — problem is WiFi or a device |
| Wired test vs package | Far below | Line, router or ISP problem |
| Local sites fast, international slow | — | International link issue (often a cable fault) |
| Slow only 8 pm–midnight | — | Network congestion |
Causes inside your home
- Weak WiFi from distance and brick or concrete walls.
- Crowded 2.4 GHz channel in apartments and dense neighbourhoods.
- Old router that cannot handle modern speeds.
- Background downloads — game updates, cloud backup, Windows Update.
- Too many devices, including smart TVs streaming in the background.
- Overheating router in summer.
Causes at your ISP
- Evening congestion on shared links.
- Line faults — corroded copper, rain damage, bent fiber.
- Distance from the exchange on DSL.
- Mobile tower congestion on 4G.
Nationwide causes
- Submarine cable damage — see cable cuts explained.
- Load shedding taking street equipment offline — see internet during load shedding.
What should I do next?
Fix home causes first (it costs nothing). If wired tests are still slow on several days, contact your ISP with screenshots, then escalate to PTA if needed.
Frequently asked questions
Why is my internet slow only at night?
More people are online between about 8 pm and midnight, so shared network links fill up.
Why is internet slow on my phone but fine on my laptop?
Usually the phone is further from the router, on 2.4 GHz, or has background app updates running.