Why your office Wi-Fi is slow, and how to improve it.

“The Wi-Fi is slow” describes at least six different faults. Some are fixed by moving a box, some by changing a setting, and one has nothing to do with Wi-Fi at all. Buying a new router before working out which fault you have is how offices end up with new equipment and the same complaint. Check in this order.

1. Is it the Wi-Fi, or the internet connection?

Plug a laptop into the router with a network cable and run a speed test. Then unplug it, stand next to the router, and run the same test over Wi-Fi.

• If both results are poor, the internet connection is the limit. Compare the cabled result with the plan you pay for, and talk to your provider.
• If the cabled result is good and the Wi-Fi result next to the router is poor, the router or its settings are the place to look. Go to steps 3 to 5.
• If both are good beside the router and bad at people’s desks, it is a coverage problem. Go to step 2.

Run the tests at the time of day people complain about. A connection that is fine at 7 am and poor at 2 pm is telling you something about how many people are using it.

2. Is it slow everywhere, or only in some places?

Wi-Fi is radio, and radio gets weaker with distance and with everything it passes through. In many offices the router sits wherever the internet line enters the building, which is seldom the middle of the floor.

Microsoft’s guidance is to move the access point towards the middle of the space and higher up, and it warns that a corner or the space under a desk reduces signal strength. It also names metal filing cabinets as a cause of interference. nbn’s list of things that weaken the signal includes thick walls of brick, concrete or metal, mirrors, and appliances such as fridges and microwaves. An office kitchen between the router and the back desks is a common example of all of those at once.

Moving the router costs nothing, so try it before anything else. If one box cannot cover the space from any position, the fix is in the last section.

3. Which band are devices using?

Most routers broadcast on two bands, and newer ones on three. Microsoft summarises the trade between the main two: 2.4 GHz has longer range and slower throughput, and 5 GHz is faster and less congested but has shorter range and does not pass through walls as well. Microwaves, cordless phones and Bluetooth devices also share the 2.4 GHz band.

A laptop a few metres from the router that has attached itself to 2.4 GHz will be slower than it needs to be. Check which band a slow device is on. Apple recommends giving every band the same network name, so that each device can move to the best band available by itself. Separate names such as “Office” and “Office-5G” leave that choice to whoever connected the device on its first day.

4. Are the neighbours on the same channel?

Each band is divided into channels, and networks on the same channel have to take turns. In a shared building, every tenancy has its own Wi-Fi within range of yours. nbn’s advice is to make sure you and your neighbours are on different channels.

On 2.4 GHz, Microsoft notes that only channels 1, 6 and 11 do not overlap one another. Apple recommends leaving channel selection on automatic, and keeping the 2.4 GHz channel width at 20 MHz, because wider channels on that band are more prone to interference from other networks. If someone has set a fixed channel or a wide channel by hand in the past, this is a setting worth resetting.

5. How many devices share one access point?

Every device on an access point shares its capacity, and the count is always higher than expected once phones, printers, televisions and tablets are included. Two things help.

First, take the devices that never move off the Wi-Fi. nbn suggests a wired connection for the heaviest users. In an office that means desktop computers, printers and the screen in the meeting room. Each one cabled is one less competing for airtime.

Second, check the age of the equipment. The Wi-Fi Alliance describes Wi-Fi 6 as giving stronger performance in dense environments, with features that share each channel more efficiently and let an access point serve more devices at once. A router from before that generation may cope with five people and struggle with twenty.

6. Is it one device?

If one laptop is slow and the one beside it is fine, the network is probably not the cause. Restart the slow one, install its pending updates, and test it on another network before changing anything in the office.

Fixing it, cheapest first

1. Move the router or access point to a central, high position with fewer walls in the way.
2. Use one network name for all bands, set channels to automatic, and set 2.4 GHz to a 20 MHz width.
3. Cable everything that stays in one place.
4. Add access points where coverage runs out. Cisco describes an access point as a way to let devices connect from further away than a router alone, and to move between access points without the connection dropping. Run a network cable to each one.
5. Replace equipment that is too old for the number of people now using it, or that no longer receives updates.

Microsoft also mentions plug-in range extenders for when the access point cannot be moved. They are quick to try in a small space. For an office with several rooms, cabled access points are the tidier fix, because each one has its own wired path back to the router.

If the office phones run over the same network, slow Wi-Fi and poor call quality often have a shared cause. See Replacing an office phone system: what to check first. Wi-Fi design and access point placement are part of Network Services, if you would like someone to measure the space and do the work.