diff --git a/src/opnsense/mvc/app/controllers/OPNsense/Base/ControllerBase.php b/src/opnsense/mvc/app/controllers/OPNsense/Base/ControllerBase.php
index 89afe9c367e..e9a905cbbbb 100644
--- a/src/opnsense/mvc/app/controllers/OPNsense/Base/ControllerBase.php
+++ b/src/opnsense/mvc/app/controllers/OPNsense/Base/ControllerBase.php
@@ -397,6 +397,7 @@ public function beforeExecuteRoute(Dispatcher $dispatcher)
         $this->view->session_username = !empty($_SESSION['Username']) ? $_SESSION['Username'] : '(unknown)';
         $this->view->system_hostname = $cnf->object()->system->hostname;
         $this->view->system_domain = $cnf->object()->system->domain;
+        $this->view->session_timeout = $this->session_timeout;
 
         if (isset($this->view->menuBreadcrumbs[0]['name'])) {
             $output = [];
diff --git a/src/opnsense/mvc/app/controllers/OPNsense/Base/ControllerRoot.php b/src/opnsense/mvc/app/controllers/OPNsense/Base/ControllerRoot.php
index 9d4c0e91c5a..cfdc63a59fb 100644
--- a/src/opnsense/mvc/app/controllers/OPNsense/Base/ControllerRoot.php
+++ b/src/opnsense/mvc/app/controllers/OPNsense/Base/ControllerRoot.php
@@ -60,6 +60,11 @@ class ControllerRoot extends Controller
      */
     protected $langcode = 'en_US';
 
+    /**
+     * @var int session timeout in seconds
+     */
+    public $session_timeout = 14400;
+
     /**
      * set system language according to configuration
      */
@@ -130,9 +135,9 @@ public function doAuth()
     {
         $cnf = Config::getInstance()->object();
         if (!empty($cnf->system->webgui->session_timeout)) {
-            $session_timeout = $cnf->system->webgui->session_timeout * 60;
+            $this->session_timeout = $cnf->system->webgui->session_timeout * 60;
         } else {
-            $session_timeout = 14400;
+            $this->session_timeout = 14400;
         }
         $redirect_uri = "/?url=" . $_SERVER['REQUEST_URI'];
         if ($this->session->has("Username") == false) {
@@ -147,7 +152,7 @@ public function doAuth()
             return false;
         } elseif (
             $this->session->has("last_access")
-            && $this->session->get("last_access") < (time() - $session_timeout)
+            && $this->session->get("last_access") < (time() - $this->session_timeout)
         ) {
             // session expired / cleanup session data
             $this->getLogger('audit')->notice(sprintf(
@@ -164,7 +169,12 @@ public function doAuth()
 
         $this->setLang();
 
-        $this->session->set("last_access", time());
+        $is_ajax = !empty($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest';
+        $is_post = $_SERVER['REQUEST_METHOD'] === 'POST';
+
+        if (!$is_ajax || $is_post) {
+            $this->session->set("last_access", time());
+        }
 
         // Authorization using legacy acl structure
         $acl = new ACL();
diff --git a/src/opnsense/mvc/app/views/layouts/default.volt b/src/opnsense/mvc/app/views/layouts/default.volt
index 1a20186c331..277d159062b 100644
--- a/src/opnsense/mvc/app/views/layouts/default.volt
+++ b/src/opnsense/mvc/app/views/layouts/default.volt
@@ -42,6 +42,7 @@
 
     <script>
             // setup default scripting after page loading.
+            window.sessionTimeout = {{ session_timeout|default('14400') }};
             $( document ).ready(function() {
                 // hook into jquery ajax requests to ensure csrf handling.
                 $.ajaxSetup({
@@ -97,6 +98,7 @@
                 addMultiSelectClearUI();
                 initGlobalOpenShortcuts();
 
+                initSessionTimeout();
                 updateSystemStatus();
 
                 // Register collapsible table headers
@@ -333,6 +335,7 @@
             searchColumns: "{{ lang._('Search columns') }}",
             expand: "{{ lang._('Click to expand/collapse cell') }}"
         });
+        localStorage.setItem('opnsense_auth_sync', Date.now().toString());
     </script>
 
   </body>
diff --git a/src/opnsense/www/js/opnsense.js b/src/opnsense/www/js/opnsense.js
index 310a5aa1b94..92933951222 100644
--- a/src/opnsense/www/js/opnsense.js
+++ b/src/opnsense/www/js/opnsense.js
@@ -370,3 +370,77 @@ function download_content(payload, filename, file_type) {
         }
     });
 }
+
+const ACTIVITY_KEY = 'opn_last_activity';
+let sessionThrottleTimer = null;
+
+let lastPingTime = Date.now();
+
+/**
+ * Resets the shared local storage timestamp.
+ */
+function resetSessionTimeout() {
+    if (!sessionThrottleTimer) {
+        sessionThrottleTimer = setTimeout(function() {
+            let now = Date.now();
+            localStorage.setItem(ACTIVITY_KEY, now.toString());
+            sessionThrottleTimer = null;
+
+            if ((now - lastPingTime) > 300000) {
+                lastPingTime = now;
+                $.post('/api/core/menu/search');
+            }
+        }, 1000);
+    }
+}
+
+/**
+ * Initializes the auto-logout tracking mechanism.
+ */
+function initSessionTimeout() {
+    if (typeof window.sessionTimeout !== 'number' || window.sessionTimeout <= 0) {
+        return;
+    }
+
+    const sessionTimeoutMs = window.sessionTimeout * 1000;
+
+    if (!localStorage.getItem(ACTIVITY_KEY)) {
+        localStorage.setItem(ACTIVITY_KEY, Date.now().toString());
+    }
+
+    $(document).on('mousemove keydown click scroll touchstart', function(e) {
+        if (e.originalEvent === undefined || e.originalEvent.isTrusted === false) {
+            return;
+        }
+        resetSessionTimeout();
+    });
+
+    // Explicit logout synchronization
+    $(document).on('click', 'a[href*="logout"]', function() {
+        localStorage.setItem('opnsense_logout', Date.now().toString());
+        localStorage.removeItem(ACTIVITY_KEY);
+    });
+
+    window.addEventListener('storage', function(e) {
+        if (e.key === 'opnsense_logout' || (e.key === ACTIVITY_KEY && !e.newValue)) {
+            window.location.reload();
+        }
+    });
+
+    setInterval(function() {
+        let activeKeyStr = localStorage.getItem(ACTIVITY_KEY);
+
+        if (!activeKeyStr) {
+            window.location.reload();
+            return;
+        }
+
+        let lastActive = parseInt(activeKeyStr, 10);
+        let timeIdleMs = Date.now() - lastActive;
+
+        if (timeIdleMs > (sessionTimeoutMs + 10000)) {
+            localStorage.removeItem(ACTIVITY_KEY);
+            window.location.reload();
+        }
+    }, 5000);
+}
diff --git a/src/www/authgui.inc b/src/www/authgui.inc
index 67cf31d9b11..c28ef808c28 100644
--- a/src/www/authgui.inc
+++ b/src/www/authgui.inc
@@ -380,7 +380,19 @@ function display_login_form($Login_Error)
     <?php if (get_themed_filename('/js/theme.js', true)) : ?>
     <script src="<?= cache_safe(get_themed_filename('/js/theme.js')) ?>"></script>
     <?php endif ?>
-
+    <script>
+        window.addEventListener('storage', function(e) {
+            if (e.key === 'opnsense_auth_sync' && e.newValue) {
+                let urlParams = new URLSearchParams(window.location.search);
+                let redirectUrl = urlParams.get('url');
+                if (redirectUrl && redirectUrl.startsWith('/')) {
+                    window.location.href = redirectUrl;
+                } else {
+                    window.location.reload();
+                }
+            }
+        });
+    </script>
   </head>
   <body class="page-login">
 
diff --git a/src/www/head.inc b/src/www/head.inc
index 9a345494124..eed55353d8b 100644
--- a/src/www/head.inc
+++ b/src/www/head.inc
@@ -112,6 +112,8 @@ $pagetitle .= html_safe(sprintf(' | %s.%s', $config['system']['hostname'], $conf
 
     <script>
     //<![CDATA[
+    window.sessionTimeout = <?= !empty($config['system']['webgui']['session_timeout']) ? $config['system']['webgui']['session_timeout'] * 60 : 14400 ?>;
+
     $( document ).ready(function() {
       $('[data-toggle="tooltip"]').tooltip();
       $("input").not("[autocomplete]").attr("autocomplete","off");
@@ -246,10 +248,15 @@ $pagetitle .= html_safe(sprintf(' | %s.%s', $config['system']['hostname'], $conf
       });
       // convert input form tables for better mobile experience
       hook_stacked_form_tables(".opnsense_standard_table_form");
+
+      initSessionTimeout();
     });
     //]]>
     </script>
 <?php if (get_themed_filename('/js/theme.js', true)): ?>
     <script src="<?= cache_safe(get_themed_filename('/js/theme.js')) ?>"></script>
 <?php endif ?>
+    <script>
+        localStorage.setItem('opnsense_auth_sync', Date.now().toString());
+    </script>
 </head>