I have a Brother MFC-J6510DW printer.
It uses the CIFS protocol for scanning.
How do I enable CIFS in the new Samba?
In OpenSuse 42.3 CIFS and Brother worked without problems.
It may be that the scanner does not support the modern samba (SMBv3) protocol.
Try adding the following entry to /etc/samba/smb.conf (‘[global]’ section)…
server min protocol = SMB2_02
That is the earliest SMBv2 version, so hopefully your scanner will work with that.
Unfortunately the printer/scanner has the old SMB protocol and “SMB2_02” doesn’t work. Fortunately it still has the FTP protocol 
Well, most wouldn’t recommend using the insecure and now deprecated SMBv1 protocol, and I’m not even sure if recent samba versions packages are built with SMB1 disabled explicitly or not. It used to be possible to allow the dialect using…
server min protocol = NT1
FTP is no safer, but if you’re using it within your own LAN behind a firewall, you may consider it reasonable (convenience vs security).