You walk from one end of the building to the other. The access point in the room you are standing in is two metres away, and your phone is still attached to the one you left behind. A video call stutters, a download runs at a third of the speed, and only turning Wi-Fi off and on again fixes it.
What it is not: this is not a connection problem and not a coverage problem. The phone has a working connection, it just has a bad one. If it really disconnects, read Wi-Fi keeps dropping. If it is slow everywhere, including sitting still, Wi-Fi is slow is the right chapter.
The quick checks, in order
- What is it attached to, and at what signal? Ask every access point:
/interface wifi registration-table print, or/interface wireless registration-table print. Find your phone's MAC address. If it shows up on the far device at -78 dBm while the nearest device does not have it at all, you have confirmed it. - Do all access points broadcast exactly the same thing? Name, security and passphrase have to match character for character. Any difference makes it a different network to the phone, so it does not roam, it reconnects, with a gap.
- Is there a controller, and does it see everything? With CAPsMAN on the wifi package:
/interface wifi capsman remote-cap print. Every access point belongs in that list. - Do the coverage areas overlap too much? Per access point, look at how many clients sit there with a strong signal. Clients at -40 dBm visible on two devices at once means they are too close together and nobody has any reason to move.
- Is 802.11r on? On the wifi package:
/interface wifi configuration printand look at the security settings of the configuration in use.
The usual causes, most common first
The client decides, and the client is lazy
This is the most important sentence in the chapter: whether a phone roams is up to the phone. An access point cannot send it next door. Most clients wait until the signal is genuinely bad, and "genuinely bad" is defined differently by every manufacturer. Everything below only nudges.
Too much transmit power
The most common mistake with several access points is running them all at maximum power. The far one then stays usable, so nothing ever has a reason to let go. Turn the power down so the cells just overlap instead of reaching across the whole building. In practice this is the change that fixes the most.
The access points do not broadcast the same thing
A space in the SSID, a different passphrase, WPA2 on one and WPA2+WPA3 on the other: every difference turns one network into two.
The client is on 2.4 GHz
2.4 GHz carries further, which is exactly why a client hangs on to a distant device there. On 5 GHz the cell is smaller and a phone gives up sooner by itself.
802.11r is off, or on with equipment that cannot take it
Fast roaming makes the handover quick, from about a second to tens of milliseconds. It does not make the decision, and some older IoT devices refuse to connect at all when it is on.
What the configurator does about it
- 802.11r fast roaming is in the Wi-Fi section, only for devices on the
wifipackage, and it is off by default there. The CAPsMAN section has the same toggle and it is on by default, because a controller implies several access points. The help text names the downside: some old IoT devices choke on it. - TX power is a field in the Wi-Fi section, in dBm, empty for the maximum allowed. This is where you turn the power down.
- In a site with several devices, the site check reports that not every access point broadcasts the same SSIDs, adding that for roaming the name, security and passphrase have to match everywhere. That is the check that catches this at the drawing stage.
- If you have a CAPsMAN controller and access points set up as standalone, the check reports that too. That combination gives you two groups of devices to maintain separately, which sooner or later means differences.
- Working in a site, the SSIDs come from one shared table. That is the simplest way to keep them identical, because you fill them in once.
What the tool does not have: there is no setting for a minimum signal below which a client is dropped, and no 802.11k or 802.11v toggle. Actively pushing a client off is work in RouterOS itself, in the radio's access list.
The honest limits
Roaming is a negotiation you do not get a vote in. You can make moving attractive, you can make it fast when it happens, but you cannot force it. A phone that sticks despite all of this is a phone that sticks. Beyond that: an extra access point only helps if it also has a decent wired uplink, and the same SSID on a repeater does nothing at all for roaming, because 802.11r, k and v do not work in that setup.
Read on: Roaming that works, CAPsMAN and Checks about Wi-Fi.