The Wi-Fi walk

Your internet provider's box usually goes where the line enters the building: the meter cupboard, the cellar, behind the bar or under the reception desk. For the connection that is fine. For Wi-Fi it is often the worst spot in the building. Proximus and Telenet both advise against putting the box in a closed cupboard and suggest a central, open place, well above the floor.

In a hotel or a café you usually cannot move the line. The usual fix is to leave the box where it is and run a network cable from it to access points in the rooms where people actually use the Wi-Fi.

Which access point a phone uses is decided by the phone itself. Most phones keep their current connection until the signal has become quite weak, and only then look around for a better one. Apple describes this for the iPhone: it starts looking when the signal drops below about -70 dBm, and it moves only when another access point is clearly stronger.

So a guest who connected in the lobby can walk to room 12, stand under the access point in that corridor, and still be talking to the one in the lobby. People in the trade call this a sticky client. The bars can look fine while pages load slowly, because the phone is using an access point at the other end of the building.

Three standards help. 802.11k hands the phone a list of nearby access points, 802.11v lets the network suggest a better one, and 802.11r makes the switch quicker. The phone still makes the decision. Some older devices will not connect at all when 802.11r is switched on, and a card terminal can be one of them, so we check your devices before we turn it on.

Adding an access point feels like the obvious fix, and in some buildings it is, but in others it makes things worse.

Two access points on the same channel that can hear each other take turns: while one sends, the other waits. The crowded 2.4 GHz band has only three or four such channels, so with a few access points on one floor and the neighbours' networks nearby, some of them end up on the same channel. Telenet gives the same warning about its own Wi-Fi pods: too few do not cover enough, and too many work against each other.

Sticky phones add a second problem. If phones already hold on to access points that are too far away, a new access point gives them one more to hold on to. Before we add hardware, we look at the channels, the power settings and which access point each phone actually uses. Sometimes the fix is to turn an access point down, or off.

Mesh systems are sets of Wi-Fi units that pass the connection from one to the next. They are easy to install because they need no cable. The price is that each extra unit gets its internet over Wi-Fi, a second wireless hop that often shares the air your guests are using. TP-Link, which sells mesh systems, puts it plainly: with a cable between the units, that link no longer uses the wireless bandwidth your devices share, so there is less delay and no bandwidth is lost to a wireless hop.

Behind thick walls the wireless link between two mesh units is often the weakest part of the whole network. Where we can, we run a cable. Where we cannot, we measure the link between the units before we rely on it.

The Wi-Fi icon on a phone turns the signal into a few bars. The phone's maker decides where each bar begins, so two phones in the same spot can show different bars. The bars tell you nothing about noise, about how busy the channel is, or about how often the phone had to send its data again. They also only describe the access point the phone happens to be connected to, which may not be the best one nearby.

A speed test is useful, but it measures the whole route to a server on the internet, including your internet line. A slow result does not tell you whether the cause is the Wi-Fi, the line or the server.

Some things matter that our current equipment cannot read, such as the noise level under the signal and how often data had to be sent again. What we can read also depends on your access points. The report says for each number what it was measured with, and it says so when something could not be measured.

We measure with a device that hears roughly what a guest's phone hears. We record access points and channels. We do not record which phones are in your building or what anyone does online.