Spotlight doesn’t automatically index network volumes. To configure spotlight to index network volumes, use the mdutil command followed by an arbitrary path, with the -i option and then the on parameter. For example, for a volume called Galvatron, you would enable indexing using the following command:

mdutil /Volumes/Galvatron -i on

To monitor the status of the indexing process:

mdutil /Volumes/Galvatron -s

If this happens to cause any problems, use the off parameter instead, along with the same command to disable indexing of that volume.

mdutil /Volumes/Galvatron -i off

You can send the mdutil commands through Apple Remote Desktop. For example, I’ve needed to toggle indexing on and then off, for which I would do something as follows via ARD:

mdutil /Volumes/Galvatron -i off; mdutil /Volumes/Galvatron -i on