Synology NAS works in DHCP, it changes the IP address once in a while.
The tweaks I made was to clear and disable (by default) all the credentials in Windous when rebooting, since the NAS can be accessed by 4 different users, so my goal is to whenever I click in the mapped drive, Windows pop up a logon screen to insert User and Password.
But although I don't have any credentials saved, Windows is not doing this.
And I still have not been able to solve the major problem: I create a mapped drive, but after rebooting, I have to do it again. This is simple stupid. My cocnlusion is that windows cannot keep mapped drives (and I even created it in command prompt with persistent option YES). So, I believe there is no way to solve, I am just about to give up.