Why is my office internet slow, and is it the broadband or the Wi-Fi?

The short answer: plug a laptop into the router with a cable and run a speed test. If it's fast on the cable but slow on Wi-Fi, the problem is your Wi-Fi. If it's slow on the cable too, the problem is your broadband connection, or something in the office using it all up.

1. Test with a cable, then with Wi-Fi

This one test tells you where to look, so it's worth doing properly.

1. Plug a laptop straight into the router with a network cable. Turn its Wi-Fi off.
2. Run a speed test (search "speed test" in your browser) and note the download and upload figures.
3. Unplug the cable, turn Wi-Fi back on, and run the test again standing near the router.
4. Run it once more from the slowest corner of the office.

If the cable result is close to what you're paying for, your connection is fine and the Wi-Fi is the weak link. If the cable result is poor too, read on to section 3.

2. If it's the Wi-Fi

Wi-Fi is the most common cause of "the internet is slow" in small offices. Typical culprits:

• Distance and walls. Thick walls, metal, glass partitions and floors all weaken the signal. A router in a cupboard at one end of the building won't reach the other end well.
• Interference. Neighbouring offices' Wi-Fi, microwaves and some older wireless kit can crowd the same channels.
• An old router. The free router from your provider may be several years old and struggle with lots of devices at once.
• Too many devices. Every laptop, phone, printer and smart TV shares the same Wi-Fi.

The fix is usually better coverage, not a faster connection. For a small space, a mesh Wi-Fi system (a few units that work together) can be enough. For a busier office, proper business access points mounted on ceilings or walls, wired back to the router, give much more reliable coverage. Where you can, put desks that never move on a cable.

3. If it's the connection

If it's slow even on a cable, a few things could be going on.

• Something is hogging it. Cloud backups, big file uploads, software updates and lots of video calls at once can fill your connection, especially the upload side. Try the cable test again when the office is empty. If it's suddenly fast, it's usage, not a fault.
• Busy times. Most broadband is "contended", meaning you share capacity with other customers. Speeds can dip at peak times. Run the test at a few different times of day to spot a pattern.
• Distance from the cabinet. On FTTC broadband, the last stretch to your building is copper, and speed drops the further you are from the green street cabinet. You can't fix that with a new router.
• You've outgrown it. A connection that suited five people may not suit fifteen who all use cloud apps and video calls.

4. Check for a fault before you upgrade

Before paying for anything, rule out a fault:

• Restart the router (off at the wall, wait a minute, back on).
• Check your provider's service status page or call them.
• Compare your cable speed test with the speed your provider estimated when you signed up. If it's well below, ask them to investigate.

Providers can often run a line test remotely and spot problems you can't see.

5. When to upgrade the connection

If there's no fault, your Wi-Fi is sorted and it's still slow when everyone's working, it's time to look at a faster or more reliable connection. Full fibre (FTTP) is a big step up where it's available, and a leased line suits businesses that can't afford slowdowns at all. See FTTC, FTTP or leased line: which do I need? for a plain comparison.

If you use phones over the internet, a slow or busy connection also shows up as choppy calls. What is VoIP? explains why voice needs a bit of priority.

Common questions

Why is my internet fast on my phone but slow on my laptop?

It's often the Wi-Fi rather than the connection. Phones and laptops can connect to different Wi-Fi bands, sit in different spots or have different Wi-Fi hardware. Run the cable test from section 1 to be sure.

Will a Wi-Fi booster help?

Sometimes, but cheap plug-in boosters often halve the speed they pass on and can make things less reliable. A mesh system or wired access points are usually a better answer for a business.

Is upload speed important?

Yes, more than most people think. Video calls, cloud backups, sending large files and saving to OneDrive or SharePoint all use upload. Many standard broadband packages have much slower upload than download, which is why the office can grind to a halt during a big backup.

How do I know if my speed is "normal"?

Compare your cable speed test with the estimate in your contract or order confirmation. If it's consistently well below that, raise it with your provider.