Recently we had to restart the main router and a couple of switches after a major upgrade. But we did not shutdown the vsphere esxi host and vcenter (as they both were in the test environment). All esxi host and vcenter are assigned static IP address, having proper DNS config, hostname is all OK. In general, all are working perfectly normal before the router/switches restart
When the switches and router are back online, I could not access any services in the vCenter. For example, I can login the vCenter web-management interface, browsing through the VMs but I cannot do the following:
1- Browse the datastore: it does not response to anything, just showing the progressing bar forever and that's it
2- Restart/shutdown a VM: it just shows the progress bar in the status but nothing happens. However, the VM cannot be access either
3- Cannot ssh into any VMs in the ESXi host
4/ Cannot restart the vCenter's VM
5/ Cannot restart the ESXi host using the builtin restart option
So I access the main config screen of the ESXi host, refresh/restart the Network; Test the connection of the DNS and Hostname, all is good. But after that, I still could not access any services either in vCenter or ESXi host.
I ended up power off the server (reboot did not work) and power on again. Then start the VMs and the vCenter. Then all is good.
I guess that the DNS server was disconnected and for some reason, the ESXi host (where the vCenter is installed on) could not reconnect to the DNS after the Router/Switches restarted. But what actually causes this and how to avoid this in the future?
Thank you very much for your advice