Fixes #11565 - Populate custom field defaults when creating FHRP groups with VIP

netbox/ipam/forms/model_forms.py

@@ -578,6 +578,7 @@ class FHRPGroupForm(NetBoxModelForm):
                 role=FHRP_PROTOCOL_ROLE_MAPPINGS.get(self.cleaned_data['protocol'], IPAddressRoleChoices.ROLE_VIP),
                 assigned_object=instance
             )
+            ipaddress.populate_custom_field_defaults()
             ipaddress.save()
 
             # Check that the new IPAddress conforms with any assigned object-level permissions

netbox/netbox/models/features.py

@@ -216,6 +216,13 @@ class CustomFieldsMixin(models.Model):
 
         return dict(groups)
 
+    def populate_custom_field_defaults(self):
+        """
+        Apply the default value for each custom field
+        """
+        for cf in self.custom_fields:
+            self.custom_field_data[cf.name] = cf.default
+
     def clean(self):
         super().clean()
         from extras.models import CustomField