A network drive mapped into a computer’s file system on a local network will not be accessible outside that network; the IP address used to connect to the device will be the local network IP address, not the global IP address.
The MyCloud used to allow remote drive mapping (using the global IP address), but this function was removed with the ‘OS3’ firmware upgrade.
I’m not sure if the drive mapping you have shown above is a local network mapping, or a global network mapping.
The only remote access now officially available is via the www.mycloud.com portal, using a web browser, or using the Mobile or Desktop Apps.
Unofficially, Nazar78’s CloudDAVMod will (I think) allow remote drive mapping:
