Using Spotlight index on a file share on Server.app I have a Mac mini server (Server.app 5.0.15 on El Capitan 10.11.2), and that connects to a file share on another Mac mini, also with El Capitan 10.11.2.

Spotlight indexes for the file shares are not available on the client, so I can't do efficient searches on the file shares.

What should be done to enable file share indexes, and where:


on the server El Capitan?
on Server.app?
on the client?


I have seen lots of discussions about successful mdutil trickery, but all are with OS X before 10.11 and Server.app before 5.0.15. My research of Apple Server Help seems to be absolutely quiet about spotlight or indexing.

What can I do have the Mac mini client index the share on another Mac that runs Server.app?
It looks like mdutil can see that server search is enabled:
$ sudo mdutil -s /Volumes/YourNetworkDrive
  /Volumes/YourNetworkDrive:
           Server search enabled.

Also the mdutil manpage has this information for the -p option:
-p  Spotlight caches indexes of some network devices locally. 
This option requests that a local caches be flushed to the
appropriate network device.

However, for me this does not seem to work, and it doesn't show remote search results anywhere when using SMB network mounts (This is in macOS Sierra).
There is one officially supported way to query remote Spotlight indexes, by using the Apple Remote Desktop application. Apple Remote Desktop is not free, but can be purchased through the Mac App Store ($79.99).
However, this a separate app and it does not integrate the remote index with local Spotlight searches. It works well though.
From the features page:

Remote Spotlight search
Leveraging the revolutionary Spotlight technology in OS X, the Remote
Spotlight capability in Apple Remote Desktop can perform
lightning-fast searches on remote client systems. Summary results for
each client are updated instantly as results are returned. View
details on results, or refine searches even further using additional
qualifiers. Results can be viewed on remote client systems, copied
back to your administrator system, or deleted.

A screenshot from the product page: