I have made a mistake by configuring the certificate and choosing all the options of TLS1 and TLS1.2 and all the checkboxes and now control panel is not working, I keep getting this error:
I unfortunately don’t know which option it is… but as a place to start, enabling those options would have set some parameters in /etc/webmin/miniserv.conf.
You may want to review the settings in there, and see if any stand out that can be removed. You may want to make a backup of that file before making any changes though.
After making changes to that file, you’d need to restart Webmin for those changes to take effect.