After so many days!!!! and after the official delegation in my country, Greece, refused to advise me over the phone, I finally found the solution. I searched here in the Xerox forum but I did not see the complete solution somewhere. So I write it, maybe someone else needs it.
After I changed the IP address : Port to 445 (old 139) – see at https://forum.support.xerox.com/t5/Copying-Faxing-Scanning/WorkCentre-6515-error-018-755/td-p/212993 - then i used Control Panel go to network and sharing center then go to change advanced sharing settings then to the section password-protected sharing finally I Disable password-protected sharing. I hope someone else finds this post helpful and did not suffer 4 days like me.
Solved! Go to Solution.
SOLUTION IN SXOLEIO'S ORIGINAL POST
Thank you for using the Support Forum.I appreciate you coming to the forum to provide this answer. I am sure other people will have less frustration than you did because you posted this solution.