Good news. I was able to connect from the LAN with https (building a certificate) using Openssl and following the instructions taken from this URL:
https://deliciousbrains.com/ssl-cert...s-development/
Once I created the certificate I inserted it in Calibre sharing over net advanced section;
Finally with
https://xxx.xxx.x.x:8080 I was able to read and download books. I have to say that https is very fast.
Now I should find the way to access from my ip pubblic.
see you soon, sonia