ESXi 6 file upload error: "failed to log into nfc server" or "failed to create session to with username and password with length" during upload of file to a datastore

During upload of file to a ESXi 6 datastore the following errors are triggered:

When using vSphere client for windows, the error "failed to log into nfc server"

OR

When using vSphere Web Client, the error "failed to create session to with username and password with length"

Solution:

Client does not sit on the same network as the ESX server.  In order to upload files using the Datastore Browser port 902 has to be opened between the client and the server.

Also, check other network related configuration between the ESXi host , vCenter and the system running the vSphere Windows or Web client