docs: def disconnect(self, si, logger, vcenter_data_model, vm_uuid, network_name=None, vm=None):
          """
          disconnect network adapter of the vm. If 'network_name' = None - disconnect ALL interfaces
          :param <str> si:
          :param logger:
          :param VMwarevCenterResourceModel vcenter_data_model:
          :param <str> vm_uuid: the uuid of the vm
          :param <str | None> network_name: the name of the specific network to disconnect
          :param <pyvmomi vm object> vm: If the vm obj is None will use vm_uuid to fetch the object
          :return: Started Task
          """
          logger.debug("Disconnect Interface VM: '{0}' Network: '{1}' ...".format(vm_uuid, network_name or "ALL"))
          if vm is None:
              vm = self.pyvmomi_service.find_by_uuid(si, vm_uuid)
              if not vm:
                  return "Warning: failed to locate vm {0} in vCenter".format(vm_uuid)
  
          if network_name:
              network = self.pyvmomi_service.vm_get_network_by_name(vm, network_name)
              if network is None:
                  raise KeyError('Network not found ({0})'.format(network_name))
          else:
              network = None
  
          network_full_name = VMLocation.combine(
              [vcenter_data_model.default_datacenter, vcenter_data_model.holding_network])
  
          default_network = self.pyvmomi_service.get_network_by_full_name(si, network_full_name)
          if network:
              return self.port_group_configurer.disconnect_network(vm, network, default_network,
                                                                   vcenter_data_model.reserved_networks,
                                                                   logger=logger)
          else:
              return self.port_group_configurer.disconnect_all_networks(vm, default_network,
                                                                        vcenter_data_model.reserved_networks,
                                                                        logger=logger)