Can the NAS do iSCSI? If so, enable iSCSI and then present iSCSI LUNs to the media server before creating the B2D on that.
Also make sure that the media server can resolve the IP/Name of the NAS via DNS, and put in entries in either DNS or the server's hosts file to get around any issues.
Furthermore, make sure that the NAS you're trying to target is actually listed on the BE 2014 HCL as being supported:
The page is cached as the Veritas is down for maintenance.....!
Lenovo EMC is simply the previous Iomega NAS. They can do iSCSI depending on the model, so maybe look into that. Something obviously changed to cause the issue. Do you have an existing B2D or can you start from scratch, in which case iSCSI works like a treat. Read my article below on how I did this with the iOmega: