SMB shares on NetApp NAS

We have a NetApp NAS in our corp network and have 12 + Mac's accessing shares on the NAS for file storage. We get user complaints that they can't open certain shares from time to time. It's like the Mac doesn't know where the share is located.

We have a mix of 10.6, Lion, Mountain Lion, and Maverick's mostly all are Mac books, all connecting to the NatApp NAS.

Has anyone seen this behavior and if so do you know what version of NetApp SMB works best for connecting Mac's to a NetApp NAS?

Do we need to configure something on the Network or on the Mac Book to allow connecting to these shares?

Also, all the Mac's are bound to our network using the standard binding protocol.

Any direction would be helpful?