An ONTAP cluster stops serving traffic with FlexCache

• ONTAP 9
• FlexCache

• Cluster stopped serving traffic unexpectedly
• All NFS mounts froze and users reported outages on their home directories
• No hardware or network issues reported, but message seen in logs:

3/7/2023 17:01:28 node-02 ERROR
    Nblade.nfsConnResetAndClose: Shutting down connection with the client. 
    Vserver ID is 9; network data protocol is mount, Rpc Xid
    0x3502d68a; client IP address:port is 10.1.2.4:591. 
    local IP address is 10.1.2.3; reason is Cannot complete export list
    processing.
3/7/2023 16:59:51 node-02 ERROR 
    Nblade.CifsOperationTimedOut: Detected a timed out CIFS operation.
    SMB command for this operation: SMB2_COM_CLOSE, Number of times this command was suspended: 2, 
    Number of times this command was restarted: 0, Last CSM error during this operation: CSM_OK, 
    Remote blade UUID: 12345678-90ab-cdef-1234-567890abcdef (macaroon-02),
    Is QoS enabled: QoS_disabled, Last nBlade error during this operation: 410, 
    Client IP address: 10.1.2.5, Local IP address: 10.1.2.3, 
    Target Vserver ID: 9, Target disk's DSID: 1135, Target Vserver Name: SVM1
3/7/2023 16:59:32 node-01 ERROR 
    sshd.loginGraceTime.expired: Timeout before password authentication for remote host 10.1.2.6.