I'm currently working on a little configuration robot for migration purposes - 7mode. There it is necessary to set option "ndmpd.enable" on the vfiler (yes vfiler!!). While other options like "httpd.enable" work fine with the current command structure, it is not possible to modify this option.
Result: Unable to set option: ndmpd.enable
Same thing happens on PowerShell command line, in WFA environment. It seems it's not possible work with this option at all.
Have you tried to run the command on the controller / vFiler and was that successful? Just trying to get a levelset and isolate if this is actually a WFA problem or a controller / vfilter configuration problem. As Tim indicated, it SHOULD work for all environments from WFA. I'm suspecting that there might be a slight configuration adjustment that might be needed for the controller / vfiler you're working with.
in the meanwhile I've found out to the set the option in a different and very easy way using "Enable-nandmp" command from WFA environment. Thus problem is resolved while it still unclear, why it's not possible to use the options setting method.
Looking at what you're trying to do, you may want to check out the Day-0 workflow example, if you haven't already. It doesn't do much with vfilers, but it may have some content in there you could use. For example, there is a WFA command in there for enabling NDMP using Enable-NaNdmp already.
The cmdlet Set-NaVfilerProtocol uses the ZAPI vfiler-allow-protocol which allows the usage of certain protocols on the vfiler (for example: nfs, cifs, rsh, iscsi).
The cmdlet Enable-NaNdmp executes the CLI command ‘ndmpd on’ which starts the ndmpd service.
Allowing the usage of a protocol using Set-NaVfilerProtocol does not necessarily enable the related service. For example, a newly created Vfiler ‘tmp’ will have the cifs protocol allowed, however you still need to run ‘cifs setup’ (Set-NaCifs) to configure and enable the CIFS service.