SSL cerificate installed via virtualmin but not working

Dear all,

I just installed a lets enrypt certificate through virtualmin control panel.
The system says that that the cerificate is installed successfully,
But when accessing the website through https, I get the following error message: ERR_SSL_PROTOCOL_ERROR.
I posted this issue in lets encrip forum and they say that this problem is related to the server not to the certificate itself. They say that my server use http instead of HTTPS.

This is the url of the mentioned website:

Could you please assist me to resolve this problem?


did you rename ssl.newkey to ssl.key in your domain?
I have all my domains with ssl certificate and allways I do it manualy using sftp with filezilla.


That method works