Hello!
I am not sure that I understand everything correctly so I ask did I right:
1. You purchased domain (internet domain name).
2. You purchased certificate for this domain.
3. You manage hoster DNS to link that domain name with your public IP in the internet in the place where your server located.
4. You allow access from the internet to the your server with specified ports.
5. You configure the application to use the certificate.
6. When you access you application web interface you see the error.
If I am right than I recommend to check that your application is accessible from the internet after you ignore the warning in the browser window.
You can also try different port number. May be you firewall occupy the chosen by you port number.
Also you can watch the full error information about certificate. Usually browsers show what they don't like. So you will be able to check where the problem is.