diff --git a/tests/test_graphql_value_mapper.py b/tests/test_graphql_value_mapper.py
index 1239e43..89d16f1 100644
--- a/tests/test_graphql_value_mapper.py
+++ b/tests/test_graphql_value_mapper.py
@@ -25,6 +25,77 @@ def test_smart_meter_maps_zigbee_channel() -> None:
     assert channel == [24]
 
 
+def _hub(connection_status: str) -> dict:
+    return {
+        "hiloId": "hub-1",
+        "deviceType": "Hub",
+        "connectionStatus": connection_status,
+        "lastConnectionTime": "2026-11-01T12:00:00Z",
+        "controllerSoftwareVersion": "1.0.0",
+        "zigBeePairingModeEnhanced": False,
+        "willBeConnectedToSmartMeter": False,
+        "smartMeterPairingStatus": False,
+    }
+
+
+def _disconnected_values(device: dict) -> set[bool]:
+    attributes = GraphqlValueMapper().map_device_subscription_values(device)
+    return {a["value"] for a in attributes if a["attribute"] == "Disconnected"}
+
+
+@pytest.mark.parametrize(
+    ("filename", "connection_status", "expected"),
+    [
+        pytest.param(
+            "onAnyDeviceUpdated-tstat.json", "CONNECTED", False, id="tstat-connected"
+        ),
+        pytest.param(
+            "onAnyDeviceUpdated-tstat.json",
+            "DISCONNECTED",
+            True,
+            id="tstat-disconnected",
+        ),
+        pytest.param(
+            "onAnyDeviceUpdated-cee.json", "CONNECTED", False, id="cee-connected"
+        ),
+        pytest.param(
+            "onAnyDeviceUpdated-cee.json", "DISCONNECTED", True, id="cee-disconnected"
+        ),
+        pytest.param(
+            "onAnyDeviceUpdated-meter.json", "CONNECTED", False, id="meter-connected"
+        ),
+        pytest.param(
+            "onAnyDeviceUpdated-meter.json",
+            "DISCONNECTED",
+            True,
+            id="meter-disconnected",
+        ),
+    ],
+)
+def test_device_disconnected_follows_connection_status(
+    filename: str, connection_status: str, expected: bool
+) -> None:
+    """Hilo reports connectionStatus as a string; DISCONNECTED maps to Disconnected=True."""
+    device = _device(filename)
+    device["connectionStatus"] = connection_status
+
+    assert _disconnected_values(device) == {expected}
+
+
+@pytest.mark.parametrize(
+    ("connection_status", "expected"),
+    [
+        pytest.param("CONNECTED", False, id="connected"),
+        pytest.param("DISCONNECTED", True, id="disconnected"),
+    ],
+)
+def test_hub_disconnected_follows_connection_status(
+    connection_status: str, expected: bool
+) -> None:
+    """The gateway's Disconnected attribute is derived from the string status."""
+    assert _disconnected_values(_hub(connection_status)) == {expected}
+
+
 @pytest.mark.parametrize(
     ("ambient_humidity", "expected"),
     [