Assuming current levels of firmware, a login failure is a login failure.
There was at one time an issue with Server 2012 using SMB where scans could work or fail dependant on pagecount, It only happened with server 2012 and with the release firmware that ended with 34540.
Beyond that I don't believe anyone can suggest anything since we have no idea on your setup, even now you haven't explained if it is SMB,FTP or either of those wrapped in Scan to home which would introduce network logins to the equation as well.