How can open Dashboard from the Internet and not from the local network?
You would have to configure your broadband router/gateway to port forward a port to the My Cloud’s web port (80). Note that your ISP may block standard ports like port 80 there by making communications with your My Cloud impossible using that port on the internet site.
There is also a security issue by opening up access to the Dashboard (or SSH for that matter) to the Internet.
Without a bit of hacking inside the NAS, the My Cloud’s software design is not to allow access to the Dashboard from outside the local network. The higher end NASs do. These being the EX2100, EX4100, DL2100 and DL4100. Possibly a few others too.
As I mentioned, it may be possible by a bit of hacking, but then WD’s software engineers may not have concentrated on the login page’s security as much as on the NASs what are designed to have dashboard access from everywhere.