I noticed UCS Manager got unexpected failover after we upgraded firmware to 2.2(2c). Looks like it hits a bug CSCuo11700. Firmware should be upgraded to 2.2.(3a) to fix the issue.
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