>>Does the NAS support multiuser-locking in databases and Opportunistic Locking? Is it configured to do so?
>
>How can I verify that?

Most NAS boxes are low-end computers running a variant of Linux. In order to provide SMB (Windows-compatible) networking, they typically run Samba: http://en.wikipedia.org/wiki/Samba_%28software%29

Whether the NAS will support multi-user lock mechanisms for Windows clients therefore depends on how Samba is configured. Although Samba is capable of supporting multi-user access, it may not be configured to do so on your NAS by default.

Many NASs are aimed at home users, who will never run multi-user applications against it so in many cases multi-user support may not be enabled. Also, performance of low-end NASs is poor, so the maker may actually disable multi-user support, which would otherwise reduce performance further.

Business-oriented NAS boxes *may* support multi-user access.

Your best bet would be to contact the manufacturer of your NAS and ask them. Or, post a message on a support forum for the device. If the issue actually is that the NAS does not by default support multi-user, then there are a few possibilities:

- if you're lucky, there may be an option in the NAS's (usually web-based) configuration tool to enable it
- the manufacturer may have instructions on how to enable it some other way
- you may need to hack the device and manually edit Samba configuration files
- worst case scenario, the NAS may not support it at all (e.g. using something other than Samba to provide SMB)

Even if you can get it working, you may find that performance of your application against the NAS is poor, unless the NAS is a high-end unit.