The Phone Stays on the Wrong Access Point: Diagnose Sticky Wi-Fi Roaming

Roaming is different from backhaul

A phone not roaming between access points needs a movement test with that specific client. Wired backhaul and a shared network name can be part of a good design, but neither guarantees that every device will transition at the desired moment.

A Reddit owner reported two iPhones sticking to a distant Asus node even though the nodes used Ethernet backhaul. A roaming-assistance change seemed to help temporarily, then the behavior returned. This is evidence for a client-specific movement test, not proof that all iPhones or all mesh systems share one defect.

The client and network features together influence roaming. Signal strength, band, supported standards, security settings, and the client’s own behavior all matter. A layout that produces impressive stationary speed can still interrupt a moving call.

Source: iPhone don't roam through the mesh (cross posted)

A roam threshold starts a search; it does not force a switch

Apple documents a −70 dBm roam trigger for iPhone 5s and later and listed iPad models, versus −75 dBm for the listed Mac families. The candidate must also be sufficiently stronger: the guide describes 8 dB for active iPhone/iPad traffic and 12 dB when idle, with 12 dB for Macs. These are documented device behaviors, not universal thresholds for every client or a guarantee of an immediate handoff.

RSSI is received signal strength. A client can remain attached because its current link has not crossed its trigger or a qualifying candidate is unavailable. Antennas and device models perceive the same room differently. Test the actual hardware and software version instead of forcing an access-point disconnect at an arbitrary number.

Source: Apple: Wi-Fi roaming support in Apple devices

Understand what 802.11k, 802.11v and 802.11r contribute

802.11k supplies neighbor information to reduce the search. 802.11v supplies information that can help a client choose a candidate. 802.11r speeds the authentication transition for supported devices. These assist different stages; enabling them does not make the access point choose the nearest radio for every client.

Reduce excessive transmit power only as part of a measured coverage design. It may reduce broad overlap, but going too far creates gaps or disconnects before another usable radio is available. Check legacy-client compatibility before enabling fast roaming and preserve a rollback for each change.

Source: Apple: Wi-Fi roaming support in Apple devices · UniFi WiFi SSID and AP Settings Overview – Ubiquiti Help Center

Reproduce the path

Use the affected phone for a consistent walking route and record its access point association before, during, and after the failure. Compare with a stationary test in the destination room. If reconnecting Wi-Fi immediately improves performance, that is useful evidence about association behavior, though not a complete diagnosis.

Ubiquiti documents fast-roaming and other wireless settings along with compatibility limits for older clients. Do not enable every advanced option at once. A setting that improves one phone can prevent an older smart device from connecting.

Source: UniFi WiFi SSID and AP Settings Overview – Ubiquiti Help Center

Illustrative scenario: a call from office to kitchen

Imagine a phone starts a call near the office access point and keeps that connection through several walls. In the kitchen, a stationary speed test looks excellent after Wi-Fi is toggled. The issue is the transition, not simply kitchen coverage.

A network assessment should evaluate overlap, transmit settings, client capabilities, and the actual roaming event. Adding an access point without reviewing overlap can leave the phone with more choices but no more predictable behavior.

Source: UniFi WiFi SSID and AP Settings Overview – Ubiquiti Help Center

Acceptance must include mobility

Agree on the applications that matter: voice calls, video meetings, or ordinary browsing. A brief packet interruption has different consequences for each. Test the relevant device generations and preserve a compatible network for legacy equipment where needed.

Record final settings and the tested walking route. Avoid promising flawless roaming for every future device. The useful claim is that specified clients completed specified tasks under observed conditions, with any remaining limitations disclosed.

Source: UniFi WiFi SSID and AP Settings Overview – Ubiquiti Help Center

Put it into practice

A decision table to keep handy