It's a protocol error, so make sure you are not trying to use port 139, it should be 445 for SMB.
And Windows 10 Usernames are always going to be Hostname\User, or Domain\User or an email address. So just verify that by adding the user to the permissions on the share and use the name as it is formatted within the brackets, not how you type it when logging in.
AN Error Code 018-505 is created when Network Scanning to PC under Win 10 using WC 7125. Which User Id has to be configured (Win Task Manager shows mail-address of active user)?