Add the webadmin subdomain Make sure Proxy Status set to DNS only if you are using cloudflare like me. Generate cert $ sudo certbot certonly --webroot -w /var/www/html -d panel.example.com First prompt, choose option "2" - Place files in webroot directory (webroot) Take those paths note down: /etc/letsencrypt/live/panel.example.com/fullchain.pem /etc/letsencrypt/live/panel.example.com/privkey.pem Change Webadmin SSL Settings Click ' adminListener ' to start. Click 'Edit' button Set Private Key File and Certificate File like so. Choose 'Yes' for Chained Certificate Click the save button once done. You will able to save your password then. That's all.