diff --git a/padelclub_backend/settings_app.py b/padelclub_backend/settings_app.py
index 231c32a..fb5212e 100644
--- a/padelclub_backend/settings_app.py
+++ b/padelclub_backend/settings_app.py
@@ -46,5 +46,5 @@ QR_CODE_CACHE_ALIAS = 'qr-code'
 
 SYNC_APPS = {
     'sync': {},
-    'tournaments': { 'exclude': ['Log', 'FailedApiCall'] }
+    'tournaments': { 'exclude': ['Log', 'FailedApiCall', 'DeviceToken'] }
 }
diff --git a/sync/consumers.py b/sync/consumers.py
index dc86e92..77cbc82 100644
--- a/sync/consumers.py
+++ b/sync/consumers.py
@@ -5,12 +5,14 @@ from channels.generic.websocket import WebsocketConsumer
 
 class UserConsumer(WebsocketConsumer):
     def connect(self):
-        self.room_name = self.scope["url_route"]["kwargs"]["user_id"]
-        self.room_group_name = f"sync_{self.room_name}"
+        self.user_id = self.scope["url_route"]["kwargs"]["user_id"]
+        self.group_name = f"sync_{self.user_id}"
+
+        print(f'connect, group_name = {self.group_name}')
 
         # Join room group
         async_to_sync(self.channel_layer.group_add)(
-            self.room_group_name, self.channel_name
+            self.group_name, self.channel_name
         )
 
         self.accept()
@@ -18,62 +20,62 @@ class UserConsumer(WebsocketConsumer):
     def disconnect(self, close_code):
         # Leave room group
         async_to_sync(self.channel_layer.group_discard)(
-            self.room_group_name, self.channel_name
+            self.group_name, self.channel_name
         )
 
     # Receive message from WebSocket
     def receive(self, data):
         # text_data_json = json.loads(text_data)
         # message = text_data_json["message"]
-        print(f'received {data}')
+        print(f'received: {data}')
 
         # Send message to room group
-        # chat.message calls the chat_message method
         async_to_sync(self.channel_layer.group_send)(
-            self.room_group_name, {"type": "sync.update", "message": "hello"} # sync.update calls the method below
+            self.group_name, {"type": "sync.update", "message": data} # sync.update calls the method below
         )
 
     # Receive message from room group
     def sync_update(self, event):
         message = event["message"]
+        print(f'event = {event}')
 
         # Send message to WebSocket
         self.send(text_data=message)
 
 
-class ChatConsumer(WebsocketConsumer):
-    def connect(self):
-        self.room_name = 'main'
-        self.room_group_name = f"chat_{self.room_name}"
+# class ChatConsumer(WebsocketConsumer):
+#     def connect(self):
+#         self.room_name = 'main'
+#         self.room_group_name = f"chat_{self.room_name}"
 
-        # Join room group
-        async_to_sync(self.channel_layer.group_add)(
-            self.room_group_name, self.channel_name
-        )
+#         # Join room group
+#         async_to_sync(self.channel_layer.group_add)(
+#             self.room_group_name, self.channel_name
+#         )
 
-        self.accept()
+#         self.accept()
 
-    def disconnect(self, close_code):
-        # Leave room group
-        async_to_sync(self.channel_layer.group_discard)(
-            self.room_group_name, self.channel_name
-        )
+#     def disconnect(self, close_code):
+#         # Leave room group
+#         async_to_sync(self.channel_layer.group_discard)(
+#             self.room_group_name, self.channel_name
+#         )
 
-    # Receive message from WebSocket
-    def receive(self, text_data):
-        # text_data_json = json.loads(text_data)
-        # message = text_data_json["message"]
-        print(f'received {text_data}')
+#     # Receive message from WebSocket
+#     def receive(self, text_data):
+#         # text_data_json = json.loads(text_data)
+#         # message = text_data_json["message"]
+#         print(f'received {text_data}')
 
-        # Send message to room group
-        # chat.message calls the chat_message method
-        async_to_sync(self.channel_layer.group_send)(
-            self.room_group_name, {"type": "chat.message", "message": text_data}
-        )
+#         # Send message to room group
+#         # chat.message calls the chat_message method
+#         async_to_sync(self.channel_layer.group_send)(
+#             self.room_group_name, {"type": "chat.message", "message": text_data}
+#         )
 
-    # Receive message from room group
-    def chat_message(self, event):
-        message = event["message"]
+#     # Receive message from room group
+#     def chat_message(self, event):
+#         message = event["message"]
 
-        # Send message to WebSocket
-        self.send(text_data=message)
+#         # Send message to WebSocket
+#         self.send(text_data=message)
diff --git a/sync/migrations/0003_modellog_device_id.py b/sync/migrations/0003_modellog_device_id.py
new file mode 100644
index 0000000..16cdb7d
--- /dev/null
+++ b/sync/migrations/0003_modellog_device_id.py
@@ -0,0 +1,18 @@
+# Generated by Django 5.1 on 2024-12-11 13:46
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('sync', '0002_remove_dataaccess_owner_dataaccess_related_user_and_more'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='modellog',
+            name='device_id',
+            field=models.CharField(blank=True, max_length=200, null=True),
+        ),
+    ]
diff --git a/sync/models/model_log.py b/sync/models/model_log.py
index 947d291..e04bf14 100644
--- a/sync/models/model_log.py
+++ b/sync/models/model_log.py
@@ -19,11 +19,10 @@ class ModelLog(models.Model):
     date = models.DateTimeField()
     model_name = models.CharField(max_length=50)
     store_id = models.CharField(max_length=200, blank=True, null=True)
-    # parent_model_id = models.UUIDField(blank=True, null=True)
-    # parent_model_name = models.CharField(max_length=50, blank=True, null=True)
+    device_id = models.CharField(max_length=200, blank=True, null=True)
 
     def save(self, *args, **kwargs):
-        # Round microseconds to milliseconds (3 decimal places)
+        # Round microseconds to milliseconds (3 decimals to match Swift precision)
         if self.date:
             microseconds = round(self.date.microsecond, -3)  # Round to nearest thousand
             self.date = self.date.replace(microsecond=microseconds)
diff --git a/sync/routing.py b/sync/routing.py
index f07a0fc..3456399 100644
--- a/sync/routing.py
+++ b/sync/routing.py
@@ -5,6 +5,6 @@ from . import consumers
 
 websocket_urlpatterns = [
     re_path(r"ws/user/(?P<user_id>[\w-]+)/$", consumers.UserConsumer.as_asgi()),
-    re_path(r"ws/chat/$", consumers.ChatConsumer.as_asgi()),
+    # re_path(r"ws/chat/$", consumers.ChatConsumer.as_asgi()),
     # re_path(r"ws/chat/(?P<room_name>\w+)/$", consumers.ChatConsumer.as_asgi()),
 ]
diff --git a/sync/signals.py b/sync/signals.py
index ef6cf07..30430a3 100644
--- a/sync/signals.py
+++ b/sync/signals.py
@@ -13,46 +13,26 @@ User = get_user_model()
 @receiver([pre_save, pre_delete])
 def synchronization_prepare(sender, instance, created=False, **kwargs):
 
+    signal = kwargs.get('signal')
+
+     # avoid crash in manage.py createsuperuser + delete user in the admin
+    if isinstance(instance, User) and (instance._state.db is None or signal == pre_delete):
+        return
+
     # some other classes are excluded in settings_app.py: SYNC_APPS
     if not isinstance(instance, BaseModel) and not isinstance(instance, User):
         return
 
-    save_model_log_if_possible(instance, kwargs.get('signal'), created)
-
-    if kwargs.get('signal') == pre_save:
-        detect_foreign_key_changes(sender, instance)
+    device_id = None
+    if hasattr(instance, '_device_id'):
+        device_id = instance._device_id
 
-def detect_foreign_key_changes(sender, instance, **kwargs):
-    if not hasattr(instance, 'pk') or not instance.pk:
-        return
-    if not isinstance(instance, BaseModel):
-        return
+    # print(f'kwargs = {kwargs}')
+    save_model_log_if_possible(instance, signal, created, device_id)
 
-    data_access_list = related_data_access(instance)
-    if data_access_list:
-        try:
-            old_instance = sender.objects.get(pk=instance.pk)
-        except sender.DoesNotExist:
-            return
-
-        # Check foreign key fields
-        for field in sender._meta.get_fields():
-            if isinstance(field, models.ForeignKey) and not field.related_model == User:
-                print(f'field.related_model = {field.related_model}')
-                old_value = getattr(old_instance, field.name, None)
-                new_value = getattr(instance, field.name, None)
-                if old_value != new_value:
-                    for data_access in data_access_list:
-                        if old_value:
-                            model_name = old_value.__class__.__name__
-                            save_model_log(data_access.shared_with.all(), 'REVOKE_ACCESS', model_name, old_value.id, old_value.get_store_id())
-                        if new_value:
-                            model_name = new_value.__class__.__name__
-                            save_model_log(data_access.shared_with.all(), 'GRANT_ACCESS', model_name, new_value.id, new_value.get_store_id())
-
-                        # REVOKE access for old_value and GRANT new_value
-                        print(f"Foreign key changed in {sender.__name__}: "
-                            f"{field.name} from {old_value} to {new_value}")
+    if signal == pre_save:
+        # print('yes')
+        detect_foreign_key_changes(sender, instance, device_id)
 
 @receiver([post_save, post_delete])
 def synchronization_notifications(sender, instance, created=False, **kwargs):
@@ -66,10 +46,10 @@ def synchronization_notifications(sender, instance, created=False, **kwargs):
     if not isinstance(instance, BaseModel) and not isinstance(instance, User):
         return
 
-    # print(f'*** signals {sender}')
-    notify_impacted_users(instance, kwargs.get('signal'))
+    # print(f'*** instance._state.db: {instance._state.db}')
+    notify_impacted_users(instance)
 
-def notify_impacted_users(instance, signal):
+def notify_impacted_users(instance):
     user_ids = set()
     # add impacted users
     if isinstance(instance, User):
@@ -80,23 +60,28 @@ def notify_impacted_users(instance, signal):
             user_ids.add(owner.id)
 
     if isinstance(instance, BaseModel):
-        if instance._users_to_notify is not None:
+        if hasattr(instance, '_users_to_notify'):
             user_ids.update(instance._users_to_notify)
         else:
             print('no users to notify')
 
+    device_id = None
+    if hasattr(instance, '_device_id'):
+        device_id = instance._device_id
+
     print(f'notify: {user_ids}')
     for user_id in user_ids:
-        websocket_sender.send_user_message(user_id)
+        websocket_sender.send_user_message(user_id, device_id)
         # send_user_message(user_id)
 
+def save_model_log_if_possible(instance, signal, created, device_id):
 
-def save_model_log_if_possible(instance, signal, created):
     if isinstance(instance, User):
         users = {instance}
     else:
         users = related_users(instance)
 
+    # print(f'users = {users}')
     if users:
         if signal == post_save or signal == pre_save:
             if created:
@@ -118,17 +103,18 @@ def save_model_log_if_possible(instance, signal, created):
 
         print(f'users to notify: {user_ids}')
         instance._users_to_notify = user_ids # save this for the post_save signal
-        save_model_log(users, operation, model_name, instance.id, store_id)
+        save_model_log(users, operation, model_name, instance.id, store_id, device_id)
 
     else:
         print('>>> Model Log could not be created because instance.last_updated_by is None')
 
-def save_model_log(users, model_operation, model_name, model_id, store_id):
+def save_model_log(users, model_operation, model_name, model_id, store_id, device_id):
     now = timezone.now()
     existing_log = ModelLog.objects.filter(users__in=users, model_id=model_id, operation=model_operation).first()
     if existing_log:
         # print(f'update existing log {existing_log.users} ')
         existing_log.date = now
+        existing_log.device_id = device_id
         # existing_log.operation = model_operation
         existing_log.save()
         existing_log.users.set(users)
@@ -139,9 +125,42 @@ def save_model_log(users, model_operation, model_name, model_id, store_id):
         model_log.model_name = model_name
         model_log.model_id = model_id
         model_log.store_id = store_id
+        model_log.device_id = device_id
         model_log.save()
         model_log.users.set(users)
 
+def detect_foreign_key_changes(sender, instance, device_id):
+    if not hasattr(instance, 'pk') or not instance.pk:
+        return
+    if not isinstance(instance, BaseModel):
+        return
+
+    data_access_list = related_data_access(instance)
+    if data_access_list:
+        try:
+            old_instance = sender.objects.get(pk=instance.pk)
+        except sender.DoesNotExist:
+            return
+
+        # Check foreign key fields
+        for field in sender._meta.get_fields():
+            if isinstance(field, models.ForeignKey) and not field.related_model == User:
+                # print(f'field.related_model = {field.related_model}')
+                old_value = getattr(old_instance, field.name, None)
+                new_value = getattr(instance, field.name, None)
+                if old_value != new_value:
+                    for data_access in data_access_list:
+                        if old_value:
+                            model_name = old_value.__class__.__name__
+                            save_model_log(data_access.shared_with.all(), 'REVOKE_ACCESS', model_name, old_value.id, old_value.get_store_id(), device_id)
+                        if new_value:
+                            model_name = new_value.__class__.__name__
+                            save_model_log(data_access.shared_with.all(), 'GRANT_ACCESS', model_name, new_value.id, new_value.get_store_id(), device_id)
+
+                        # REVOKE access for old_value and GRANT new_value
+                        print(f"Foreign key changed in {sender.__name__}: "
+                            f"{field.name} from {old_value} to {new_value}")
+
 def delete_data_access_if_necessary(model_id):
     DataAccess.objects.filter(model_id=model_id).delete()
 
@@ -155,9 +174,12 @@ def handle_shared_with_changes(sender, instance, action, pk_set, **kwargs):
     elif action == "post_remove":
         instance.create_access_log(users, 'REVOKE_ACCESS')
 
+    device_id = None
+    if hasattr(instance, '_device_id'):
+        device_id = instance._device_id
+
     for user_id in pk_set:
-        websocket_sender.send_user_message(user_id)
-        # send_user_message(user_id)
+        websocket_sender.send_user_message(user_id, device_id)
 
 @receiver(pre_delete, sender=DataAccess)
 def revoke_access_after_delete(sender, instance, **kwargs):
@@ -171,10 +193,12 @@ def related_users(instance):
         users.add(instance.related_user)
         users.add(instance.last_updated_by)
 
+        # look in hierarchy
         related_instances = instance.related_instances()
         related_users = [ri.related_user for ri in related_instances if isinstance(ri, BaseModel)]
         users.update(related_users)
 
+        # look in related DataAccess
         data_access_list = instances_related_data_access(instance, related_instances)
         for data_access in data_access_list:
             users.add(data_access.related_user)
diff --git a/sync/utils.py b/sync/utils.py
index 69acbad..ec1ab77 100644
--- a/sync/utils.py
+++ b/sync/utils.py
@@ -34,7 +34,7 @@ def get_data(model_name, model_id):
     return model.objects.get(id=model_id)
 
 def get_serialized_data(model_name, model_id):
-    print(f'model_name = {model_name}')
+    # print(f'model_name = {model_name}')
     model = sync_registry.get_model(model_name)
     instance = model.objects.get(id=model_id)
     serializer_class = build_serializer_class(model_name)
diff --git a/sync/views.py b/sync/views.py
index 5a0bce0..bb35a49 100644
--- a/sync/views.py
+++ b/sync/views.py
@@ -85,9 +85,9 @@ class SynchronizationApi(HierarchyApiView):
         model_operation = request.data.get('operation')
         model_name = request.data.get('model_name')
         data = request.data.get('data')
-        # store_id = request.data.get('store_id')
+        device_id = request.data.get('device_id')
 
-        print(f"DataApi post > {model_operation} {model_name}")
+        print(f"DataApi post > {model_operation} {model_name}, device: {device_id}")
 
         serializer_class = build_serializer_class(model_name)
         data['last_updated_by'] = request.user.id # always refresh the user performing the operation
@@ -98,13 +98,15 @@ class SynchronizationApi(HierarchyApiView):
         if model_operation == 'POST':
             serializer = serializer_class(data=data, context={'request': request})
             if serializer.is_valid():
-                serializer.save()
+                instance = serializer.save()
+                instance._device_id = device_id
                 return Response(serializer.data, status=status.HTTP_201_CREATED)
             else:
                 return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
         elif model_operation == 'PUT':
             data_id = data.get('id')
             instance = get_data(model_name, data_id)
+            instance._device_id = device_id
             serializer = serializer_class(instance, data=data, context={'request': request})
             if serializer.is_valid():
                 if instance.last_update <= serializer.validated_data.get('last_update'):
@@ -120,6 +122,7 @@ class SynchronizationApi(HierarchyApiView):
             data_id = data.get('id')
             try:
                 instance = get_data(model_name, data_id)
+                instance._device_id = device_id
                 instance.delete()
                 return Response(status=status.HTTP_204_NO_CONTENT)
             except model.DoesNotExist: # POST
@@ -131,6 +134,7 @@ class SynchronizationApi(HierarchyApiView):
 
     def get(self, request, *args, **kwargs):
         last_update_str = request.query_params.get('last_update')
+        device_id = request.query_params.get('device_id')
         decoded_last_update = unquote(last_update_str)  # Decodes %2B into +
 
         # print(f'last_update_str = {last_update_str}')
@@ -144,7 +148,7 @@ class SynchronizationApi(HierarchyApiView):
 
         print(f'/data GET: {last_update}')
 
-        logs = self.query_model_logs(last_update, request.user)
+        logs = self.query_model_logs(last_update, request.user, device_id)
         print(f'>>> log count = {len(logs)}')
 
         updates = defaultdict(dict)
@@ -220,9 +224,10 @@ class SynchronizationApi(HierarchyApiView):
         print(f'response_data = {response_data}')
         return Response(response_data, status=status.HTTP_200_OK)
 
-    def query_model_logs(self, last_update, user):
-        # print(f'last_update = {last_update}')
-        log_query = Q(date__gt=last_update) & Q(users=user)
+    def query_model_logs(self, last_update, user, device_id):
+        log_query = Q(date__gt=last_update, users=user)
+        if device_id:
+            log_query &= Q(device_id=device_id)
         return ModelLog.objects.filter(log_query).order_by('date')
 
 class UserDataAccessApi(HierarchyApiView):
diff --git a/sync/ws_sender.py b/sync/ws_sender.py
index b22da39..833cee5 100644
--- a/sync/ws_sender.py
+++ b/sync/ws_sender.py
@@ -10,10 +10,11 @@ class WebSocketSender:
         self._user_timers = {}   # Dictionary to store user-specific timers
         self._buffer_timeout = 0.1  # Debounce timeout in seconds
 
-    def send_user_message(self, user_id):
+    def send_user_message(self, user_id, device_id):
         """
         Schedules a notification for a specific user with debouncing.
         """
+        print(f'>>> send message: {device_id}')
         # Cancel existing timer for this user if any
         if user_id in self._user_timers and self._user_timers[user_id]:
             self._user_timers[user_id].cancel()
@@ -22,23 +23,26 @@ class WebSocketSender:
         self._user_timers[user_id] = Timer(
             self._buffer_timeout,
             self._send_message,
-            args=[user_id]
+            args=[user_id, device_id]
         )
         self._user_timers[user_id].start()
 
-    def _send_message(self, user_id):
+    def _send_message(self, user_id, device_id):
         """
         Sends the WebSocket message for a specific user.
         """
         channel_layer = get_channel_layer()
         group_name = f"sync_{user_id}"
-        print(f">>> send to group {group_name}")
+
+        print(f">>> send to group {group_name}, device_id={device_id}")
+        # print(f'channel_layer = {channel_layer}')
+
+        device_id = device_id if device_id else "std_msg_lol" # a not empty message is required!
 
         async_to_sync(channel_layer.group_send)(
             group_name,
-            {"type": "sync.update", "message": "hello"}
+            {"type": "sync.update", "message": device_id}
         )
-
         # Cleanup timer reference
         self._user_timers[user_id] = None
 
diff --git a/tournaments/migrations/0107_remove_devicetoken_creation_date_and_more.py b/tournaments/migrations/0107_remove_devicetoken_creation_date_and_more.py
new file mode 100644
index 0000000..e0efc20
--- /dev/null
+++ b/tournaments/migrations/0107_remove_devicetoken_creation_date_and_more.py
@@ -0,0 +1,29 @@
+# Generated by Django 5.1 on 2024-12-11 16:39
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('tournaments', '0106_club_related_user_court_related_user_and_more'),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name='devicetoken',
+            name='creation_date',
+        ),
+        migrations.RemoveField(
+            model_name='devicetoken',
+            name='last_update',
+        ),
+        migrations.RemoveField(
+            model_name='devicetoken',
+            name='last_updated_by',
+        ),
+        migrations.RemoveField(
+            model_name='devicetoken',
+            name='related_user',
+        ),
+    ]
diff --git a/tournaments/models/device_token.py b/tournaments/models/device_token.py
index 625fe8c..d350376 100644
--- a/tournaments/models/device_token.py
+++ b/tournaments/models/device_token.py
@@ -3,7 +3,7 @@ from . import CustomUser
 import uuid
 from . import BaseModel
 
-class DeviceToken(BaseModel):
+class DeviceToken(models.Model):
     user = models.ForeignKey(CustomUser, on_delete=models.CASCADE, related_name='device_tokens')
     value = models.TextField()