diff --git a/tests/assets/config_full.json b/tests/assets/config_full.json
index b545b36..d4284dc 100644
--- a/tests/assets/config_full.json
+++ b/tests/assets/config_full.json
@@ -25,7 +25,7 @@
             "watt": 2000,
             "beep": true
         },
-        "update_interval": 30,
+        "update_interval": 15,
         "beep_volume": 5,
         "auto_reboot": false,
         "sync_cache": true
diff --git a/tests/test_wmconfig.py b/tests/test_wmconfig.py
index 5bc3e34..46f49ed 100644
--- a/tests/test_wmconfig.py
+++ b/tests/test_wmconfig.py
@@ -143,7 +143,7 @@ def test_load_full(self):
         self.assertTrue(config.config.wattmeter.warning.beep)
         self.assertEqual(config.config.wattmeter.caution.watt, 2000)
         self.assertTrue(config.config.wattmeter.caution.beep)
-        self.assertEqual(config.config.wattmeter.update_interval, 30)
+        self.assertEqual(config.config.wattmeter.update_interval, 15)
         self.assertEqual(config.config.wattmeter.beep_volume, 5)
         self.assertFalse(config.config.wattmeter.auto_reboot)
         self.assertTrue(config.config.wattmeter.sync_cache)
@@ -178,7 +178,7 @@ def test_load_min(self):
         self.assertEqual(config.config.wattmeter.max.watt, 3000)
         self.assertIsNone(config.config.wattmeter.warning)
         self.assertIsNone(config.config.wattmeter.caution)
-        self.assertEqual(config.config.wattmeter.update_interval, 15)
+        self.assertEqual(config.config.wattmeter.update_interval, 30)
         self.assertEqual(config.config.wattmeter.beep_volume, 3)
         self.assertTrue(config.config.wattmeter.auto_reboot)
         self.assertFalse(config.config.wattmeter.sync_cache)
diff --git a/wattmeter/meter.py b/wattmeter/meter.py
index ff1ca6b..2f3615f 100644
--- a/wattmeter/meter.py
+++ b/wattmeter/meter.py
@@ -167,10 +167,15 @@ def _updateTime(self):
             # エラーの記録だけ行いタスクループの停止(例外の送出)はしない
             self.logging.e(e)
 
-    def _prepareClient(self):
+    def _prepareClient(self, force_scan=False):
         """
         Wi-SUNクライアントの使用準備を行う
 
+        Parameters
+        ----------
+        force_scan : bool
+            SKSCANを強制的に実行する場合はTrue
+
         Raises
         ------
         WiSUNError
@@ -199,8 +204,11 @@ def _prepareClient(self):
         self.client.execSetRbId(self.config.config.b_route.id)
 
         cache = self.config.cache
-        if None in (cache.channel, cache.pan_id, cache.mac_addr):
-            self.logging.info("cache miss: scan results")
+        if force_scan or None in (cache.channel, cache.pan_id, cache.mac_addr):
+            if force_scan:
+                self.logging.info("force scan")
+            else:
+                self.logging.info("cache miss: scan results")
             self.vlcd.showProgress(11 / total_steps, "Scanning...")
             self.utime.sleep(self.SCAN_PRE_WAIT_SEC)
             retry_count = self.SCAN_RETRY
@@ -245,7 +253,7 @@ def _prepareClient(self):
                     retry_count -= 1
                     self.logging.info("BP35A1 join retry: " + str(retry_count))
                     continue
-                raise e
+                raise JoinError(str(e))
         self.vlcd.showProgress(17 / total_steps, "Connected")
 
         self.logging.info("BP35A1 get meter status")
@@ -332,7 +340,13 @@ def prepare(self):
         self.logging.info("<<< _prepareNtp()")
 
         self.logging.info(">>> _prepareClient()")
-        self._prepareClient()
+        try:
+            self._prepareClient()
+        except JoinError as e:
+            self.logging.exception(e)
+            # SKJOIN失敗時はSKSCAN強制実行ありで1回だけリトライする
+            self.logging.info("retry _prepareClient(True)")
+            self._prepareClient(True)
         self.logging.info("<<< _prepareClient()")
 
         self.logging.info(">>> _prepareTask()")
@@ -827,4 +841,10 @@ class WiSUNError(Exception):
     """
     pass
 
+class JoinError(Exception):
+    """
+    SKJOIN失敗時の例外
+    """
+    pass
+
 # <<< meter
diff --git a/wattmeter/wmconfig.py b/wattmeter/wmconfig.py
index c766623..5cb273a 100644
--- a/wattmeter/wmconfig.py
+++ b/wattmeter/wmconfig.py
@@ -48,7 +48,7 @@ class WMConfig:
             },
             "warning": None,
             "caution": None,
-            "update_interval": 15,
+            "update_interval": 30,
             "beep_volume": 3,
             "auto_reboot": True,
             "sync_cache": False,