Dashboard: Device Analytics: 5GHz client shown under "Unknown" band

[kateatlinksys]

Reproduce steps:

1. Login to Linksys Now.
2. Connect one client to 2.4GHz and one to 5GHz (single router, no mesh).
3. Go to Dashboard > Device Analytics > Distribution and Signal tabs.

Actual result:
The 5GHz client is shown under "Unknown" instead of "5GHz" — Distribution shows "2.4GHz: 1 / Unknown: 1 / Wired: 3". (The 2.4GHz client classifies correctly.)

Expected result:
"2.4GHz: 1 / 5GHz: 1 / Wired: 3".

Env.: M60DU-EU / Pinnacle 2.0 FW 1.2.2.26062820 / Linksys Now 2.5.0.700525

Log:
GUI_wifiperformance_error_0715.txt

Screenshot:

[AustinChangLinksys]

🔍 Automated investigation (preliminary triage)

Line: 2.x / USP (TR-369)

Root cause:

• Trigger (firmware side): the Device.WiFi.AccessPoint.2.AssociatedDevice.* subtree (5GHz AP) is never populated. Clients that are actually on 5GHz are either listed under AccessPoint.1 (2.4GHz) or point at an AccessPoint.2.AssociatedDevice.1 instance whose MACAddress row never exists.
• UI defect: _computeDistribution in usp_device_analytics_notifier.dart buckets each WiFi client by d.band ?? 'Unknown'. d.band is filled in usp_devices_data_service.dart from the AccessPoint→SSID→Radio chain. When a 5GHz client can't be resolved through that chain (because AP.2 has no usable AssociatedDevice entry), band is null and the client falls into the literal "Unknown" bucket instead of being reconciled against Hosts.Layer1Interface, which firmware does report correctly as Radio.2.

Evidence (from attached log.txt):

1. Distribution derivation buckets on d.band and defaults missing bands to 'Unknown' (lib/page/_shared/providers/usp_device_analytics_notifier.dart L127-129):

for (final d in wifiDevices) {
  final band = d.band ?? 'Unknown';
  bandDist[band] = (bandDist[band] ?? 0) + 1;

2. band is resolved only via AssociatedDevice → AccessPoint → SSID → Radio (usp_wifi_data_service.dart L374-378):

final band = ssid != null
    ? (bandByRadioPath[_ensureTrailingDot(ssid.lowerLayers)] ?? '')
    : '';
result[mac] = ClientConnectionDetail(band: band, ssidName: ssidName);

3. Firmware never lists the 5GHz client under AccessPoint.2 — a whole-log scan finds zero AccessPoint.2.AssociatedDevice.*.MACAddress keys, so the 5GHz client has no band to resolve and lands in "Unknown". Meanwhile the Hosts table DOES place it on Radio.2 (L2967, L2991):

"Device.Hosts.Host.6.Layer1Interface": "Device.WiFi.Radio.2",
"Device.Hosts.Host.6.AssociatedDevice": "Device.WiFi.AccessPoint.2.AssociatedDevice.1",

Confidence: Medium — the firmware AssociatedDevice table for the 5GHz AP is empty/inconsistent versus the Hosts + DataElements tables, so firmware-side confirmation is needed. Shares the same firmware root cause as #1136 (5GHz AP association not reported); the UI could also harden by falling back to Hosts.Layer1Interface for band.

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Auto-generated triage by Austin's tooling, pending Austin's review. Not a fix commitment.