The errors displayed seem to indicate a problem with a CIFS/SMB mount (which you probably have configured as a storage in PVE):
* check it's logs
* check the journal of the PVE-node for more hints (or the syslog)
You seem to have a storage of type CIFS configured on your system - see '/etc/pve/storage.cfg' for which it is.
CIFS/SMB is a networking filesystem - it has a server (PVE is the client) - check the logs of the CIFS server!