Unable to attach VMs to an NSX-T Segment: "An error occurred during host configuration"

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• VMs can connect to standard and distributed port groups without any issues.
• When trying to connect a VM to an NSX segment, the connection fails.
• The following error message is observed:
  

Environment

NSX-T

VMware vCenter server

Cause

Connectivity between the NSX-T Manager and the ESXi hosts was blocked. It was identified that the hosts were in a disconnected state in NSX-T. To reconfigure the VM with NSX-T port groups, the hosts must be in a connected state in NSX-T.]

Resolution

• Enable the necessary ports between the NSX-T Manager and the vCenter (VC) to establish proper communication.
  For detailed port requirements, please refer to: NSX-T Ports.
• After the required ports were opened, the ESXi hosts were brought online in NSX-T, and their status changed to "connected" in vCenter.
• The VM was then successfully reconfigured with NSX-T port groups.