Well, to save everyone else the trouble (since it isn’t documented anywhere – and I just spent about an hour finding the cause for this), if you need to configure NDMP on your NetApp Filer, make sure you also configure an interface other than e0M.
Apparently the necessary controlport for NDMP (10000) is being blocked on e0M, thus ndmp may be configured and running, however TSM is gonna complain that it is unable to connect to the specified data mover.
ANR4728E Server connection to file server 172.31.76.100 failed. Please check
the attributes of the file server specified during definition of the datamover.
ANR2146E DEFINE DATAMOVER: Node NAS_DM is not registered.
ANS8001I Return code 11.