On my NAS, I have UPnP working. In myQNAPcloud app, Secure Web Server is OK with ports to 8081 for internal and 8083 for external. On my box (Livebox 5), I have the same parameters in the UPnP tab. On the DDNS tab of myQNAPcloud app, there are an IPV4 address and an IPV6 address but when I test ports redirection, the Secure Web Server is ok on port 8083 for IPV4 but not for IPV6.
I this why my share link does not work outside my home ? How do I do to my share link works out of my home ?
This gives you a share link that puts QNAPs servers as a proxy between your NAS and the outside world. Anyone downloading the file never has direct access of any kind to your NAS.