Short answer: on a mesh or multi-access-point network, each device decides for itself when to switch to a closer unit, and most wait until the signal is fairly weak. Apple’s iPhones and iPads hold on to their current access point until the signal falls past about −70 dBm, and Macs until −75 dBm. To get devices to switch sooner, use one network name, turn on your system’s roaming features, and avoid placing nodes so they each cover far more than they need to.

Who decides: the device, not the router

It’s tempting to think the mesh system moves your phone to the nearest node. In practice the device makes the call. Apple says its devices decide when to roam by comparing the signal strength of the current access point with others on the same network.

And they’re patient. An iPhone or iPad keeps its current connection until the signal falls past −70 dBm; a Mac waits until −75 dBm. Only then does it look for a better one. Other makers’ devices use their own thresholds; Juniper Mist, which makes enterprise Wi-Fi systems, notes that some treat −75 dBm as the point to start looking.

If those numbers mean nothing to you yet, how to check your Wi-Fi signal strength explains the dBm scale and how to read it on your devices.

Why it happens so often on mesh

The result is a phone in the bedroom still using the node in the living room, at a fraction of the speed the bedroom node could give it.

The roaming helpers: 802.11k, v and r

Three Wi-Fi standards help devices roam better, and Apple’s devices support all of them:

  • 802.11k gives the device a list of nearby access points, so it doesn’t have to scan every channel.
  • 802.11v lets the network suggest a better access point.
  • 802.11r (often called fast roaming or fast transition) makes the switch itself quicker, which helps during a call.

If your system has a “fast roaming” or similar setting and it’s off, turning it on is the first fix to try. If a device stops connecting after you enable it, turn the setting back off.

How to fix a device that won’t switch

1. Use one network name everywhere

Apple recommends a single network name across all bands and all access points. Devices only roam within the same network, so separate names for each node or band stop roaming altogether.

2. Use your system’s roaming setting

Some routers can nudge devices off a weak connection. ASUS, for example, explains that with several access points, devices sometimes stay on the main router instead of the best one, and its Roaming Assistant disconnects a device whose signal drops below a threshold (−70 dBm by default) so that it reconnects to a stronger one. Other systems have similar options; check your app’s advanced Wi-Fi settings.

3. Rethink placement

If devices cling to one node across most of the house, the nodes may be closer together than they need to be, or the main node may be very central and very strong. Moving a node, or measuring signal in the problem rooms, often helps more than any setting. How many mesh nodes you need and where to put your router and nodes cover the planning side.

4. Nudge stationary devices

Devices that don’t move, such as a smart TV or a desktop, connect once and rarely re-check. If one is on the wrong node, turn its Wi-Fi off and on, or restart it, so it makes a fresh choice.

When it isn’t roaming

If a device loses its connection entirely rather than staying on a far node, that’s a different problem: see Wi-Fi keeps disconnecting. And if every node is slow, look at the link between the units: mesh backhaul explained.