diff --git a/homeassistant/components/device_tracker/asuswrt.py b/homeassistant/components/device_tracker/asuswrt.py
index 495e377077f..f49f54b3622 100644
--- a/homeassistant/components/device_tracker/asuswrt.py
+++ b/homeassistant/components/device_tracker/asuswrt.py
@@ -177,10 +177,10 @@ class AsusWrtDeviceScanner(DeviceScanner):
         """
         devices = {}
         devices.update(self._get_wl())
-        devices.update(self._get_arp())
-        devices.update(self._get_neigh())
+        devices = self._get_arp(devices)
+        devices = self._get_neigh(devices)
         if not self.mode == 'ap':
-            devices.update(self._get_leases())
+            devices.update(self._get_leases(devices))
         return devices
 
     def _get_wl(self):
@@ -194,7 +194,7 @@ class AsusWrtDeviceScanner(DeviceScanner):
             devices[mac] = Device(mac, None, None)
         return devices
 
-    def _get_leases(self):
+    def _get_leases(self, cur_devices):
         lines = self.connection.run_command(_LEASES_CMD)
         if not lines:
             return {}
@@ -208,30 +208,45 @@ class AsusWrtDeviceScanner(DeviceScanner):
             if host == '*':
                 host = ''
             mac = device['mac'].upper()
-            devices[mac] = Device(mac, device['ip'], host)
+            if mac in cur_devices:
+                devices[mac] = Device(mac, device['ip'], host)
         return devices
 
-    def _get_neigh(self):
+    def _get_neigh(self, cur_devices):
         lines = self.connection.run_command(_IP_NEIGH_CMD)
         if not lines:
             return {}
         result = _parse_lines(lines, _IP_NEIGH_REGEX)
         devices = {}
         for device in result:
-            mac = device['mac'].upper()
-            devices[mac] = Device(mac, None, None)
-        return devices
+            if device['mac']:
+                mac = device['mac'].upper()
+                devices[mac] = Device(mac, None, None)
+            else:
+                cur_devices = {
+                    k: v for k, v in
+                    cur_devices.items() if v.ip != device['ip']
+                }
+        cur_devices.update(devices)
+        return cur_devices
 
-    def _get_arp(self):
+    def _get_arp(self, cur_devices):
         lines = self.connection.run_command(_ARP_CMD)
         if not lines:
             return {}
         result = _parse_lines(lines, _ARP_REGEX)
         devices = {}
         for device in result:
-            mac = device['mac'].upper()
-            devices[mac] = Device(mac, device['ip'], None)
-        return devices
+            if device['mac']:
+                mac = device['mac'].upper()
+                devices[mac] = Device(mac, device['ip'], None)
+            else:
+                cur_devices = {
+                    k: v for k, v in
+                    cur_devices.items() if v.ip != device['ip']
+                }
+        cur_devices.update(devices)
+        return cur_devices
 
 
 class _Connection:
@@ -348,8 +363,9 @@ class TelnetConnection(_Connection):
                 self.connect()
 
             self._telnet.write('{}\n'.format(command).encode('ascii'))
-            return (self._telnet.read_until(self._prompt_string).
+            data = (self._telnet.read_until(self._prompt_string).
                     split(b'\n')[1:-1])
+            return [line.decode('utf-8') for line in data]
         except EOFError:
             _LOGGER.error("Unexpected response from router")
             self.disconnect()