You mentioned all 3 stopped SMB scanning at once, which makes it unlikely it is the machine(s).
These steps will verify the access and folder permissions (within Windows):
How-To Test Login to SMB Share from Command Prompt
*Use a workstation other than the one hosting the share*
To see if you can login to the share, map a drive, k in this example:
If testing a local user
net use k:(space)\\server\share(space)/user:server\username(space)*
If testing a domain user
net use k:(space)\\server\share(space)/user:Domain\username(space)*
(NOTE: placing the asterisk at the end of the string means that it will prompt for the password of the user)
To see if you can Read, Write,Delete:
Change to the mapped drive by typing k:
List the contents of the share: dir
See if you can write to the share: mkdir (directory_name)
Confirm that the new directory was created: dir
Delete the directory you created: rmdir (directory_name)
Confirm that the directory was deleted: dir
To disconnect (unmount) the mapped drive:
net use k:(space)/delete
If you haven't already fixed this issue, I did search our online knowledge base and found this article for SMB scanning that may assist you.
Alternatively, you can visit our Contact Us page for other support options.
Deeply asking for your support with my Xerox AltaLink C8030 machines.
Once all 3 machines stopped scanning to the SMB folder.
I did upgrade of firmware and installed the latest patch, so now I am on 103.001.020.23120
I reset the machine (erase customer data) and start from the beginning:
add a contact to address book - which is an SMB folder at Windows Server 2016.
username is added as domain\user
destination test shows Failed: Cannot Login into destination server using credentials provided.
Credentials, folder and user permissions are 100% checked.