Check netgear device_tracker link_rate to ensure device is connected (#30581)

* check link_rate to ensure device is connected

* black

homeassistant/components/netgear/device_tracker.py

@@ -110,7 +110,10 @@ class NetgearDeviceScanner(DeviceScanner):
                     or dev.name in self.excluded_devices
                 )
             )
-            if tracked:
+
+            # when link_rate is None this means the router still knows about
+            # the device, but it is not in range.
+            if tracked and dev.link_rate is not None:
                 devices.append(dev.mac)
                 if (
                     self.tracked_accesspoints