DLm health check report failing most Data Domain checks

All administrative access to the Data Domain via ssh fails, but the NFS mount points remain active.

                        System Reporting Alert: vte1
                        Brief Description: DLm error level event number DLMF:DLmT0307E: SSH Keys Check Failed: SSH keys not distributed to DD system.
                        DLm HEALTH CHECK RESULTS for System APM01204708239 2021-04-07 at 15:56:51 (5.3.0-4)
...
            DD Management Connection Check                            FAILED
                        Failed to connect dd1                                      
                        dd1                                                           FAILED

            DD Data Connection Check                                            PASSED
                        DD-1 192.168.203.111 Connection Check                   PASSED
                        DD-1 192.168.203.112 Connection Check                   PASSED
                        DD-1 192.168.203.113 Connection Check                   PASSED
                        DD-1 192.168.203.114 Connection Check                   PASSED
                        DD-1 192.168.203.115 Connection Check                   PASSED
                        DD-1 192.168.203.116 Connection Check                   PASSED
                        DD-1 192.168.203.117 Connection Check                   PASSED

            NFS Mounts Check                                              PASSED
                        /lockfs/LOCK                                           Host dd1s: Available
                        /opt/DLm/DD-1/dlmconfig                               Host dd1s: Available
                        /tapelibPRD/DD1_P1_FS1                                 Host dd1s-alias0: Available
                        /tapelibPRD/DD1_P1_FS2                                 Host dd1s-alias1: Available
                        /tapelibPRD/DD1_P1_FS3                                 Host dd1s-alias2: Available
                        /tapelibPRD/DD1_P1_FS4                                 Host dd1s-alias3: Available

            ...
            Check SSH Keys Distribution                                          FAILED
                        root@vte2 to sysadmin@dd-1                        FAILED
                        vtape@vte2 to sysadmin@dd-1                                   FAILED
...
            DD Management Connection Check                            FAILED
                        Failed to connect dd1                                      
                        dd1                                                           FAILED

            DD Data Connection Check                                            PASSED
                        DD-1 192.168.203.111 Connection Check                   PASSED
                        DD-1 192.168.203.112 Connection Check                   PASSED
                        DD-1 192.168.203.113 Connection Check                   PASSED
                        DD-1 192.168.203.114 Connection Check                   PASSED
                        DD-1 192.168.203.115 Connection Check                   PASSED
                        DD-1 192.168.203.116 Connection Check                   PASSED
                        DD-1 192.168.203.117 Connection Check                   PASSED

...
Data Domain 1:
Cannot check Data Domain 1:
Cannot access dd1


Errors found during Healthcheck:

VTE 1
            Check SSH Keys Distribution                                          FAILED
                        root@vte1 to sysadmin@dd-1                        FAILED
                        vtape@vte1 to sysadmin@dd-1                                   FAILED
VTE 1
            DD Management Connection Check                            FAILED
                        Failed to connect dd1                                      
                        dd1                                                           FAILED
VTE 2
            Check SSH Keys Distribution                                          FAILED
                        root@vte2 to sysadmin@dd-1                        FAILED
                        vtape@vte2 to sysadmin@dd-1                                   FAILED
VTE 2
            DD Management Connection Check                             FAILED
                        Failed to connect dd1                                      
                        dd1                                                           FAILED
Data Domain 1
            Cannot check Data Domain 1                                        Cannot access dd1

Command line access to the Data Domain similarly fails:
ssh sysadmin@dd1
ssh_exchange_identification: read: Connection reset by peer

The unit IS reachable by ping and telnet over port 22.  

All SSH access to the Data Domain was restricted via Data Domain System Manager ; Administration ; Access ; SSH.  The DLm requires all vte management ip addresses to have ssh access.

ssh access restrictions on the Data Domain MUST permit all DLm VTE internal management network IP addresses within the 192.168.100.* range as documented in the DLm /etc/hosts file on the primary management VTE.

Verify any SSH restrictions via the DLm attached Data Domain System Manager ; Administration ; Access ; SSH panel.  If there are SSH restrictions, then SSH access MUST permit all VTE ip addresses.