First, enable a key manager
Then convert all data volumes to NVE
volume encrypt start ….
After that, be sure any svm root volumes have been moved to the same aggregate.
Then convert the aggregates without the svm to NAE -> aggregate modify -aggregate xx -encrypt
Move the svm root
Vol move start -volume svmroot -dest aggr-nae -encrypt-with-aggr-key true
Encrypt the last aggregate
Now convert all the volumes to nae:
Vol move start -Vol xx -dest same-as-source -encrypt-with-aggr-key true
If you do not do the last step, you will not have full NAE. There is a kb about this as well