PowerScale SyncIQ: All policies fail with error "No node on source cluster was able to connect to target cluster" when Source or Target cluster is running OneFS 9.1

SyncIQ source or target cluster was recently upgraded to OneFS 9.1.0 or later.

All policies fail with error:      
No node on source cluster was able to connect to target cluster.

The SyncIQ log /var/log/isi_migrate.log shows "attempting to run an unencrypted" message:        

2021-01-27T18:41:05Z <3.3> btestin-1(id1) isi_migrate[33253]: secondary: Source 1XX.1XX.1.69 is attempting to run an unencrypted sync while the global required flag is set.
2021-01-27T18:41:36Z <3.3> btestin-1(id1) last message repeated 5 times
2021-01-27T19:05:27Z <3.3> btestin-1(id1) isi_migrate[33253]: secondary: Source 1XX.1XX.1.69 is attempting to run an unencrypted sync while the global required flag is set.

In OneFS 9.1 and later, SyncIQ sets the encryption required flag to yes by default:       

# isi sync settings view
                                 Service: on
                           Source Subnet: -
                             Source Pool: -
                         Force Interface: No
                 Restrict Target Network: No
                       Tw Chkpt Interval: -
                          Report Max Age: 1Y
                        Report Max Count: 2000
                              RPO Alerts: Yes
                     Max Concurrent Jobs: 32
Bandwidth Reservation Reserve Percentage: 1
  Bandwidth Reservation Reserve Absolute: -
                     Encryption Required: Yes
                  Cluster Certificate ID:
              OCSP Issuer Certificate ID:
                            OCSP Address:
                  Encryption Cipher List:
                    Renegotiation Period: 8H
                 Service History Max Age: 1Y
               Service History Max Count: 2000
                    Use Workers Per Node: No

There are two options to address this issue.

• Configure policies to use encryption. See KB article 21507: Isilon OneFS: How to configure SyncIQ policies to use SSL encryption

• Change the encryption required flag in SyncIQ.

btestin-1# isi sync settings view
                                 Service: on
                           Source Subnet: -
                             Source Pool: -
                         Force Interface: No
                 Restrict Target Network: No
                       Tw Chkpt Interval: -
                          Report Max Age: 1Y
                        Report Max Count: 2000
                              RPO Alerts: Yes
                     Max Concurrent Jobs: 16
Bandwidth Reservation Reserve Percentage: 1
  Bandwidth Reservation Reserve Absolute: -
                     Encryption Required: No
                  Cluster Certificate ID:
              OCSP Issuer Certificate ID:
                            OCSP Address:
                  Encryption Cipher List:
                    Renegotiation Period: 8H
                 Service History Max Age: 1Y
               Service History Max Count: 2000
                    Use Workers Per Node: No