diff --git a/docs/user/device-checks-and-alert-settings.rst b/docs/user/device-checks-and-alert-settings.rst
index addc0f58..a579cc5a 100644
--- a/docs/user/device-checks-and-alert-settings.rst
+++ b/docs/user/device-checks-and-alert-settings.rst
@@ -1,6 +1,59 @@
 Managing Device Checks & Alert Settings
 =======================================
 
+**Overview of default checks**
+
+1. Ping Check
+-------------
+* **Triggers when**: Value is less than 1
+* **Wait time**: 0 minutes (immediate)
+* **Sets status**: Critical
+* **Meaning**: Device is unreachable
+
+2. Config Applied Check
+-----------------------
+* **Triggers when**: Value is less than 1
+* **Wait time**: 5 minutes
+* **Sets status**: Problem
+* **Meaning**: Configuration hasn't been updated for over 5 minutes
+
+3. WiFi Clients Check
+---------------------
+Maximum:
+^^^^^^^^
+* **Triggers when**: More than 50 clients
+* **Wait time**: 120 minutes (2 hours)
+* **Sets status**: Problem
+* **Meaning**: Too many clients connected
+
+Minimum:
+^^^^^^^^
+* **Triggers when**: Less than 1 client
+* **Wait time**: 0 minutes (immediate)
+* **Sets status**: Problem
+* **Meaning**: No clients connected
+
+4. Disk Usage Check
+-------------------
+* **Triggers when**: Usage exceeds 90%
+* **Wait time**: 0 minutes (immediate)
+* **Sets status**: Problem
+* **Meaning**: Disk space is nearly full
+
+5. Memory Usage Check
+---------------------
+* **Triggers when**: Usage exceeds 95%
+* **Wait time**: 5 minutes
+* **Sets status**: Problem
+* **Meaning**: High memory consumption persists
+
+6. CPU Usage Check
+------------------
+* **Triggers when**: Usage exceeds 90%
+* **Wait time**: 5 minutes
+* **Sets status**: Problem
+* **Meaning**: High CPU load persists
+
 We can add checks and define alert settings directly from the **device
 page**.
 
diff --git a/openwisp_monitoring/device/base/models.py b/openwisp_monitoring/device/base/models.py
index 1d263da4..bb97ee83 100644
--- a/openwisp_monitoring/device/base/models.py
+++ b/openwisp_monitoring/device/base/models.py
@@ -319,10 +319,7 @@ def save_wifi_clients_and_sessions(self):
                 active_sessions.append(session_obj.pk)
 
         # Close open WifiSession
-        WifiSession.objects.filter(
-            device_id=self.id,
-            stop_time=None,
-        ).exclude(
+        WifiSession.objects.filter(device_id=self.id, stop_time=None,).exclude(
             pk__in=active_sessions
         ).update(stop_time=now())