Controller service on Manager node vmwNsxTDataCenterApplianceAddress (vmwNsxTDataCenterCentralControlPlaneId) to Transport node vmwNsxTDataCenterTransportNodeName (vmwNsxTDataCenterEntityId) down for at least 15 minutes from Controller service's point of view. Action required: 1. Check the connectivity from the Controller service vmwNsxTDataCenterCentralControlPlaneId and Transport node vmwNsxTDataCenterEntityId interface via ping and traceroute. This can be done on the NSX Manager node admin CLI. The ping test should not see drops and have consistent latency values. VMware recommends latency values of 150ms or less. 2. Navigate to System | Fabric | Nodes | Transport node vmwNsxTDataCenterEntityId on the NSX UI to check if the TCP connections between the Controller service on Manager node vmwNsxTDataCenterApplianceAddress (vmwNsxTDataCenterCentralControlPlaneId) and Transport node vmwNsxTDataCenterEntityId is established. If not, check firewall rules on the network and the hosts to see if port 1235 is blocking Transport node vmwNsxTDataCenterEntityId connection requests. Ensure that there are no host firewalls or network firewalls in the underlay are blocking the required IP ports between Manager nodes and Transport nodes. This is documented in our ports and protocols tool which is here: https://ports.vmware.com/.