On the server

nfsd: last server has exited
May 18 18:33:51 centos kernel: nfsd: unexporting all filesystems
May 18 18:33:51 centos kernel: NFSD: Using /var/lib/nfs/v4recovery as the NFSv4 state recovery directory
May 18 18:33:52 centos kernel: NFSD: starting 90-second grace period


On the client
CIFS VFS: Send error in SessSetup = -13
May 18 18:25:29 backup kernel:  CIFS VFS: cifs_mount failed w/return code = -13
May 18 18:25:35 backup kernel:  CIFS VFS: Send error in SessSetup = -13
May 18 18:25:35 backup kernel:  CIFS VFS: cifs_mount failed w/return code = -13