To this point at KNIME we are still unable to reproduce the issue as it seems to only happen with some file servers, e.g. certain NetApp appliances.
We did an upgrade of the smbj library update with 4.6.0 which seems to cause this. The new smbj defaults to using SMB3, whereas the previous version preferred SMB2. Our current hypothesis that this is causing the issue. We are currently adding a way to force SMB2 to the SMB Connector node, which will be released with AP 4.6.2.