Thank you very much for your support.
I am talking about two different systems, each one with their own computers, different MC licenses, both using a sinology Diskstation. Mine in Lisbon, my brotherīs about 250 Km away. Mine has about two years, his is new.
They are exactly settled the same way (by me). Mine works without any problem and I can asses my NAS from my 3 machines, each one with MC installed.
My brother has 2 computers, his own MC licenses and a Sinology like mine, just a newer model. In one of the computers everything runs fine. He rips disks and the files are stored on the NAS and his Library (a new one that I created) is on MC.
The other computer is exactly settled the same way: he can import the library, play the CD etc.
But, when he shuts down the MC and opens it again, all the library is disappears.
He has to import again or to restore the library, witch is not practical at all.
I made my research and found that the problem might be related to have enabled Party Mode. But I can' find if it is enabled and if it is, how to disable it.
So, please, with this information and your knowledge, please try to hel me, without a radical solution.
Kind regards