vCenter upgrade prechecks on the SDDC manager are failing because Witness host is not accessible on ports 22, 443

Products

• VMware SDDC Manager

Issue/Introduction

• Workload domain is configured with a stretch cluster and Witness host.
• A number of prechecks are reported as  "vSphere SHA-1 validation" and "Verify Standalone Host topology".
• Operation manager python validations logs reports a failure to connect to a witness host:
  Failed to connect to host <Witness_FQDN>.

Environment

VMware SDDC Manager

Cause

 SDDC-M is doing the prechecks by retrieving the list of hosts from the vCenter inventory and connect to them from ports 443 and 22 to retrieve their information.

Resolution

Direct connectivity is required to ports 443, 22 from the SDDC-M to the Witness Host.