"The internet is slow" describes a symptom with at least four different causes. Working out which one you have takes twenty minutes and saves a long conversation with a provider about the wrong thing.

Test properly first

Most speed tests are done wrongly and produce a number that means nothing.

Use a cable. Plug a laptop directly into the router. A test over wi-fi measures your wi-fi, which may be the actual problem but is a different problem.

Stop everything else. No streaming, no downloads, no cloud backup running. One device, one test.

Test several times. Morning, afternoon and mid-evening. A connection fine at 10am and poor at 8pm is a contention pattern, which is a different fault from one that is consistently slow.

Record what you get, with times and dates. This is what you will need later.

Also note the upload figure, not just download. Consumer connections are heavily asymmetric, and upload is what limits video calls and cloud backups.

Then work through the causes in order

1. Is it the connection itself?

If the wired test is well below what you pay for, consistently, at all times of day — the problem is upstream of your house.

Compare against your provider's minimum guaranteed speed, which they were required to give you when you signed up. That figure, not the advertised "up to" number, is what matters contractually.

2. Is it contention?

If the wired test is good in the morning and poor in the evening, capacity in your area is being shared.

This is normal to a degree and excessive if the drop is severe. It is worth reporting with evidence, because providers do upgrade capacity where enough people complain with data.

3. Is it your wi-fi?

If the wired test is fine and wireless is poor, the connection is not the problem.

Test in the same room as the router and then in the problem room. A large difference confirms a coverage issue, addressed in home wi-fi that covers the whole house.

4. Is it one device?

If everything else is fine and one laptop is slow, the laptop is the problem. Old wireless hardware, a full disk, too many programs starting automatically, or an ageing machine — see slow laptop: repair or replace.

5. Is something in the house using it all?

The commonest cause of an unexplained afternoon slowdown. A games console downloading an update, a cloud backup running, a television buffering, an automatic operating system update.

Many routers show which devices are consuming bandwidth. Look before assuming.

The thing speed tests do not measure

A connection can test at 500 megabits and still be useless for video calls, because speed is not the only property that matters.

Latency is how long a round trip takes. High latency makes everything feel sluggish regardless of speed.

Packet loss is data that fails to arrive and must be resent. Even one or two per cent ruins calls and gaming while barely affecting a download, because a download simply asks again and a live conversation cannot.

Jitter is variation in latency, which is what produces the robotic audio on calls.

If downloads are fine but calls are bad, you have one of these rather than a speed problem — and telling your provider "downloads are fine, calls break up" points them at the right thing immediately.

A speed test that looks good does not exonerate a connection. Loss and jitter ruin calls while leaving the headline number untouched.

Things worth trying before ringing anybody

  • Restart the router, properly — off for a minute. Genuinely fixes a proportion of problems.
  • Check the master socket. On older connections, plugging directly into the master socket removes internal wiring from the equation. A large difference means the fault is inside your house.
  • Replace the cable from the socket to the router. Cheap, and they degrade.
  • Check for a filter on older lines — a missing or failed microfilter causes exactly this.
  • Look for physical damage to the incoming line, particularly after weather.

What to say to your provider

Evidence rather than description. Providers respond to specifics.

Give them: your wired speed test results with dates and times, a comparison against your minimum guaranteed speed, what you have already tried, and whether the problem is constant or at particular times.

Ask them specifically to check the line for errors and to confirm the speed profile applied to your connection. Ask what your minimum guaranteed speed is and whether you are receiving it.

If they cannot resolve a persistent shortfall within the period their code of practice allows, you are usually entitled to leave without penalty. Mentioning that you are aware of this frequently changes the conversation.

If a fault is intermittent, continuous monitoring produces far better evidence than occasional tests — the same principle as network monitoring for small businesses.

Our support team diagnoses connection problems across Suffolk and Norfolk, including the intermittent ones providers say are not there. Get in touch.