Just noticed a issue that nothing reported in 'Hardware Status' tab of ESXi hosts in vSphere Web Client. KB 2112847 gives a solution but not works for me. The feature can be used to monitor hardware failures. I figured out a way to workaround it. You just need to login by Administrator account and click 'Update' button under 'Monitor' - 'Hardware Status' for each ESXi host. You will get the status after few minutes.
When you run Connect-NsxtServer in the PowerCLI, it may show "Unable to connect to the remote server". Because the error message is a little bit confusing with other login issues. It's not easy to troubleshoot. The actual reason is the NSX-T uses a self-signed certificate, and the PowerCLI cannot accept the certificate automatically. The fix is super easy. You need to set the PowerCLI to ignore the invalid certificate with the following command: Set-PowerCLIConfiguration -Scope User -InvalidCertificateAction:Ignore -Confirm:$false