I created a NAS user account with a username that is also an email address (e.g. nasuser1@qnap.com). Why is this user unable to access the NAS from a Mac computer?
This problem is caused by how Mac computers handle the ‘at’ symbol (@).
When accessing a QNAP NAS from a Mac via SMB, the Mac treats “nasuser1” as the username and “@qnap.com” as the domain name. This causes NAS authentication to fail, preventing an SMB connection from being established.
To work around this problem, do not use the ‘at’ symbol (@) in NAS usernames.
For further assistance, ask other users and QNAP experts in the community. Go to QNAP Community