Problems in getting SSL cert for custom HTTP server

  acme, c++, https, ssl, windows

For my own needs C++ TCP Win server was developed. It serve for a lot of aims, including HTTP server(using cpp-httplib).
I did not need secure connection previously, so it worked without certificates. I used my external static IP and port forwarding on my home router and it works well!

Now I need to create a secure connection.

Google suggested to use Windows ACME (WACS) to get cert.

cpp-httplib is also supporting HTTPS connections so, in theory, there should be no problems =)

However, in process of cert creation, I need to specify the domain. But all I have is IP and when I specify IP as domain WACS gives an error "The ACME server cannot issue a certificate for the IP address".

I am an absolute newbie in creating an HTTPS server, I’ll be glad for any advice and links, but firstly I am searching answers for following questions:

  1. Did I choose the right way? is it possible at all to create server with secure connection for free?
  2. Can I create a domain from my IP without my own DNS server?
  3. Is it possible to get ready certificate or a .pem file, in example, for student’s?
  4. What problems will I faced next? At least I can already see that the certificate needs to be updated/renewed each 90 days.

Source: Windows Questions