Why your fibre feels slow — and how to fix it

Fibre is the fastest and most consistent connection technology available, so when it feels slow the cause is usually somewhere between the router and the device rather than on the line itself.

This guide works through the possibilities in order of how often they turn out to be responsible.

First, test properly

Almost every speed investigation goes wrong at the first step. A test run over Wi-Fi from the far end of the house measures your Wi-Fi, not your fibre.

1. Plug a laptop into the router with an Ethernet cable. This removes Wi-Fi from the equation entirely and is the single most valuable thing you can do.
2. Pause everything else. Stop downloads, streaming, cloud backups and console updates on every device in the house.
3. Run the test three times. Once now, once during the evening peak, and once late at night. Use our speed test or any reputable tester.
4. Write down each result with the time. The pattern across the day tells us far more than a single number.

Cause 1: Wi-Fi, by a wide margin

This is the most common answer. Wi-Fi is affected by distance, walls, interference from neighbours, the age of your devices and how many things are connected.

• Move the router somewhere central, high and in the open — see improving your Wi-Fi signal.
• Use the 5 GHz band for devices in the same room; it’s considerably faster.
• If one end of the house is weak, consider mesh or an additional access point.
• Reduce the number of connected devices, particularly older ones that slow the whole network down.

Cause 2: the device you’re testing on

• An older laptop with a 100 Mbps network port physically cannot exceed about 94 Mbps regardless of your line.
• Phones and tablets more than a few years old often support only 2.4 GHz Wi-Fi, which caps real-world speeds well below fibre rates.
• A device low on storage or memory, or running many background applications, will test slowly for reasons unrelated to your connection.
• Test on a second device before concluding anything. If one device is slow and everything else is fine, the device is the problem.

Cause 3: everything else in the house

Home packages are shared across everyone using them. A single 4K stream can consume 25 Mbps, a console game update can saturate the line completely, and a cloud backup running quietly in the background will slow everything without any obvious cause.

• Check what’s running on other devices before assuming a fault.
• Schedule large downloads and backups for overnight.
• If your household has grown since you signed up, the package may simply be too small now.

Cause 4: peak-hour patterns

If speeds are excellent at 10:00 and poor at 20:00 every day, that’s a peak-hour pattern. It may be your own household’s usage, or it may be capacity in your area — and that’s something we want to know about.

Report it with cabled test results from several evenings and the corresponding off-peak results. That evidence lets us check capacity on your access node directly rather than guessing.

Cause 5: the package no longer fits

Sometimes nothing is wrong at all. A 10 Mbps package that was ample for two people is genuinely inadequate for a family of five with a home office and three streaming devices. The line is delivering exactly what it should — there just isn’t enough of it.

If that’s the situation, we’ll tell you honestly. Ask us about upgrading — in most cases it takes effect within 24 hours and needs no new installation.

Reporting a speed problem to us

• Three or more speed test results with the time of day noted
• Whether each test was on a cable or over Wi-Fi
• Which devices are affected and which aren’t
• Whether the problem is constant or follows a daily pattern
• What you’ve already tried

With that information, log a fault and our team can usually get to the answer quickly.