private void test(){

  foreach (Device device in project.Devices)

  {

    foreach(DeviceItem item in GetDeviceItems(device.DeviceItems))

    {

      var nwService = item.GetService<NetworkInterface>();

      MessageBox.Show(item.Name & " " &nwService?.Nodes.ToString());

    }

}

private IEnumerable<DeviceItem> GetDeviceItems(DeviceItemComposition items)

{

  foreach(DeviceItem item in items){

    yield return item;

    foreach(DeviceItem subItem in GetDeviceItems(item.DeviceItems)){

      yield return subItem;

    }

  }

}

Edit: Many device items has device items, so yo need to check every device item for items unless you know the item and use e.g. Find method. First you have device which is e.g. Et200/S7-1500 station. First device item is Rail not PLC.