diff --git a/openwisp_controller/config/api/serializers.py b/openwisp_controller/config/api/serializers.py
index ff62ff1cb..d3b285def 100644
--- a/openwisp_controller/config/api/serializers.py
+++ b/openwisp_controller/config/api/serializers.py
@@ -254,6 +254,7 @@ def update(self, instance, validated_data):
                         instance.config.vpnclient_set.exclude(vpn__in=vpn_list).delete()
                     instance.config.templates.clear()
                     instance.config.templates.add(*[])
+            instance.config.save()
 
         elif hasattr(instance, 'config') and validated_data.get('organization'):
             if instance.organization != validated_data.get('organization'):
diff --git a/openwisp_controller/config/tests/test_api.py b/openwisp_controller/config/tests/test_api.py
index 854130e9b..a427ff3c6 100644
--- a/openwisp_controller/config/tests/test_api.py
+++ b/openwisp_controller/config/tests/test_api.py
@@ -200,7 +200,7 @@ def test_device_put_api(self):
             'organization': org.pk,
             'mac_address': d1.mac_address,
             'config': {
-                'backend': 'netjsonconfig.OpenWrt',
+                'backend': 'netjsonconfig.OpenWisp',
                 'status': 'modified',
                 'templates': [],
                 'context': '{}',
@@ -212,6 +212,11 @@ def test_device_put_api(self):
         self.assertEqual(r.status_code, 200)
         self.assertEqual(r.data['name'], 'change-test-device')
         self.assertEqual(r.data['organization'], org.pk)
+        self.assertEqual(r.data['config']['backend'], 'netjsonconfig.OpenWisp')
+        d1.refresh_from_db()
+        self.assertEqual(d1.name, 'change-test-device')
+        self.assertEqual(d1.organization, org)
+        self.assertEqual(d1.config.backend, 'netjsonconfig.OpenWisp')
 
     # test device with VPN-client type template assigned to it
     def test_device_with_vpn_client_template_assigned(self):