diff --git a/openwisp_monitoring/check/classes/iperf.py b/openwisp_monitoring/check/classes/iperf.py
index acfecfed3..38f12562b 100644
--- a/openwisp_monitoring/check/classes/iperf.py
+++ b/openwisp_monitoring/check/classes/iperf.py
@@ -27,7 +27,6 @@ def check(self, store=True):
                 f'DeviceConnection is not properly set for "{device}", iperf check skipped!'
             )
             return
-        device_connection.connect()
         # The DeviceConnection could fail if the management tunnel is down.
         if not device_connection.connect():
             logger.warning(
@@ -40,6 +39,9 @@ def check(self, store=True):
             command, raise_unexpected_exit=False
         )
         if store and exit_code != 0:
+            logger.warning(
+                f'Iperf check failed for "{device}", {json.loads(res)["error"]}'
+            )
             self.store_result_fail()
             device_connection.disconnect()
             return
@@ -51,6 +53,9 @@ def check(self, store=True):
                 command, raise_unexpected_exit=False
             )
             if store and exit_code != 0:
+                logger.warning(
+                    f'Iperf check failed for "{device}", {json.loads(res)["error"]}'
+                )
                 self.store_result_fail()
                 device_connection.disconnect()
                 return
diff --git a/openwisp_monitoring/monitoring/configuration.py b/openwisp_monitoring/monitoring/configuration.py
index aabd5870c..5199859c1 100644
--- a/openwisp_monitoring/monitoring/configuration.py
+++ b/openwisp_monitoring/monitoring/configuration.py
@@ -582,11 +582,11 @@ def _get_access_tech():
                     'total': 'lines',
                 },
                 'trace_order': ['total', 'received', 'sent'],
-                'description': _('Total transfer during Iperf3 test in TCP mode.'),
+                'description': _('Transfer during Iperf3 test in TCP mode.'),
                 'summary_labels': [
+                    _('Total bytes'),
                     _('Received bytes'),
                     _('Sent bytes'),
-                    _('Total upload traffic'),
                 ],
                 'unit': _(' GB'),
                 'order': 290,