Going though the backlog of things to log about, I found this from 2014.
The issue you are seeing is because your SAMBA File Servers are not part of our Active Directory Domain.
So the SAMBA shares folks are connecting to are not within the MSWINDOWS domain, there is no trust relationship between MSWINDOWS and your SAMBA workgroup/domains. Microsoft Windows by default will always attempt to connect or reconnect with the logged-in users domain credentials (ie. MSWINDOWS) first, IF you do not supply your Samba domain\user credentials.
Lockout occurs from your end when a certain number of incorrect authentication attempts are detected.
So what you should do is map your SAMBA network drives as a different user from Windows explorer, explicitly specifying the Workgroup (“SAMBAPC\userid” in the case of shares to SAMBAPC) or domain (“SAMBADOMAIN\userid” for everything else) for the relevant user.
If this is done it generally avoids the issue.
Still true 4 years later.