VCF 9.0 Deployment of NSX Workload Domain in unable to proceed with error message “IP address and default gateway must be on the same subnet.”

Products

• VMware SDDC Manager
• VCF Operations
• VMware NSX

Issue/Introduction

While attempting to deploy a new NSX Workload Domain following Create a New Workload Domain Using VCF Operations:

• The VCF Operations Interface accepts all configurations, particularly the chosen NSX Manager IP addresses and default gateway.
• The VCF Operations Interface performs the expected forward and reverse DNS lookups
• The VCF Operations Interface rejects the chosen Appliance Cluster Virtual IP Address and Gateway with the message: "IP address and default gateway must be on the same subnet."
  
• The chosen NSX Manager and default gateway IP addresses are on the same subnet.

Environment

• VMware vCloud Foundation 9.0
• VMware VCF Operations 9.0
• VMware NSX 9.0

Cause

VCF 9 expects all management components, even workload management, to be on the same management network as the VCF Operations and vCenter components.  This error message is comparing the chosen IP addresses of the NSX Managers with the VCF Operations gateway and finding them on different subnets.

Resolution

Deploy the NSX Manager components for the Workload domain on the same network as the VCF Management components.