While deploying your own certificate on ESXi server you need to follow certain requirement to create it as shown here, if new generated certificate is not correct as per the standard and if they are replaced overwritten without proper backup, it can cause connection error on ESXi server and you will see error similar to This site can't be reached, refused to connect with ERR_CONNECTION_REFUSED.
Generate new self-signed certificates for ESXi using OpenSSL
Push SSL certificates to client computers using Group Policy
Replacing a default ESXi certificate with a CA-Signed certificate
Troubleshooting replacing a corrupted certificate on Esxi server
How to import default vCenter server appliance VMCA root certificate and refresh CA certificate on ESXi
How to replace default vCenter VMCA certificate with Microsoft CA signed certificate
To resolve it immediately open ssh session to ESXi server and run command /sbin/generate-certificates, which will restore and generate default self-signed certificate in location /etc/vmware/ssl. To take effect run command services.sh restart &tail -f /var/log/jumpstart-stdout.log.
After checking once again on browser, everything should be good and esxi website will be working again.
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