Roaming Wi-Fi: why the phone keeps a weak signal
The phone passes through the office, past two access points with a strong signal, and then sticks to the third, weakest one. This is not a bug, but the way Wi-Fi roaming works in the company: the decision is made by the client device, not the network. This article explains the mechanism, shows what can be done about it on the network side, and says directly what cannot be done.
The decision is made by the device, not the network
One sentence explains most of the reports on this topic: on the network Wi-Fi is customer decideswhich access point to connect to and when to switch, and the network can help it, and even nudge it to do so, but it cannot decide on its behalf.
Manufacturers of end devices implement this logic differently and do not disclose its details, which is why a phone from one brand will behave differently from another, and a laptop will behave differently from both, even though they are all placed in the same place.
Therefore, the question "why isn't my phone switching" doesn't have an answer on the network side, but does have an answer on how that particular phone's software is designed.
Why devices stick to weak signal
From the perspective of the device itself, this behaviour is completely rational.
Switching to another access point means a momentary interruption in transmission, as you have to disconnect from one, find the other, authenticate and reconnect, all of which takes time and, at an unfortunate moment, can interrupt the conversation or transfer.
So the device tries to avoid this by maintaining the existing connection as long as something can be sent over it, even if there is something much better next to it. This phenomenon is sometimes called the "sticky customer".
The effect visible to the user comes down to an apparent contradiction: full lines and slow action. The dashes describe the signal level of the device to which the phone is connected, not the fact that there is a better connection waiting somewhere nearby.
Why it's not just one person's problem
This is worth naming because it changes the repair priority.
A device operating at the edge of the range transmits at the lowest speeds, and Wi-Fi networks operate on a common medium in which one device transmits on a given channel at a time, while the rest waits. Because a slow transmitting device consumes the medium longer than a fast transmitting device, one laptop stuck to a distant access point can slow down the work of all those using the same channel.
Roaming is not a matter of convenience for a single user, but a matter of the efficiency of the entire network.
What can be done on the network side
Four things, ordered from the most effective.
1. Correct the arrangement
Most effective and most often skipped because it doesn't involve changing any setting.
If the coverage areas are edge-to-edge instead of overlapping, the device passes through a weak signal zone on both sides on the way between them, so there is no good time to switch. However, if the access point hangs where its signal carries much further than it should, such as at the end of a long corridor, devices from the other end of the building will stick to it.
Placement is resolved on the object, not the directory. We write more about the selection itself in the article about how many access points are needed in the office.
2. Set the minimum signal threshold
Network management platforms allow you to set a level below which the access point disconnects the client, and the disconnected device searches for a new connection and usually chooses a closer point.
The mechanism works, but requires caution because a threshold set too aggressively causes disconnections, resulting in users reporting the exact symptom that was supposed to disappear. The value is therefore selected for a specific object and verified after implementation, instead of setting it by guess.
3. Enable band steering
Devices often default to the 2.4 GHz band because it carries farther, although it is narrower, more crowded and slower.
Band steering encourages higher band devices to use them, not by being forced but by refusing to respond on a lower band when the client is seen on a higher one.
You must remember about the limitation: some equipment, especially older and industrial ones, only supports 2.4 GHz, so too restrictive a setting may cut off sensors, printers or production devices.
4. Enable roaming support mechanisms
The Wi-Fi standards provide mechanisms to help the client make a decision: providing a list of neighboring access points, suggesting a transition and shortening the re-authentication procedure.
These work well, but they have two conditions. First, they must be supported by the client device itself, which newer phones and laptops typically do, while older hardware varies. Secondly, on some older devices, turning them on causes connection problems, so it is worth verifying the implementation rather than assuming it will work.
What can't be fixed
Let's say it straight because it saves money.
Cannot force device to switch; they can be disconnected, but this is a blunt tool and fraught with side effects. You also can't fix roaming by adding access points, because a denser, poorly distributed network worsens the problem by giving the device more candidates with similar signal strength. It's impossible to improve the behaviour of a specific phone model, so if the problem affects one type of device while the rest work fine, the problem is in that device. Finally, it cannot be resolved remotely, because roaming is revealed in traffic, and verification requires walking the route with the device.
How to check if it's really roaming Wi-Fi in your company
The "weak signal" symptom has several causes, and it's worth separating them before anyone changes anything.
| Observation | Points to |
|---|---|
| The problem is only in traffic, in place it's fine | roaming |
| Problem in a specific place, also while standing | cover or obstruction |
| Problem at specific times, regardless of location | network or link load |
| Problem only on one type of device | software for this device |
| The problem with the cable also occurs | is not a wireless layer |
The last line is the most important and the cheapest to check. The full path of layer separation is described in the article about what to do when your corporate network is slow.
What to prepare before reporting
Before the conversation, it is worth determining where the problem occurs and where it does not, whether it occurs when moving or also when there is no movement, on which devices and whether other devices in the same place work properly. It is also useful to know whether anything has changed recently, for example, new walls or shelves have been added, devices have been added or a new neighbor has appeared in the building, and finally, where the access points are physically located.
These five pieces of information weed out most false leads before anyone arrives.
How we do it
Roaming is verified in motion by walking the route on which the problem is reported, using a device of the type used by the company, because the measurement made from a laptop standing still describes a completely different situation than working conditions.
We start with the placement, because that's where most of the causes lie, and we treat the threshold and band control settings as a correction, not as a solution. After each change, we verify the result rather than assuming it worked.
In corporate networks, we are a Zyxel Networks Partner and we also implement Ubiquiti UniFi.
Roaming is also a good example of why it's worth keeping an eye on your network, as a new partition or moved shelf changes radio conditions without any change to the configuration, and the symptom appears weeks later. With ongoing care, this can be seen in the data before the report is received.
Scope: building and maintaining corporate networks and constant IT care.
Book a free IT review And let's figure out how to see if it's roaming or something else.