It's actually very easy to set up a TLS server using certificates from Let's Encrypt or any other ACME-compliant certificate provider. If you're using Apache, mod_md[0] will manage all the details for you. After enabling mod_md and mod_ssl, a simple TLS server only requires a few lines of extra configuration compared to a basic non-TLS site:

  MDCertificateAgreement accepted
  MDomain example.org
  <VirtualHost *:443>
    ServerName example.org
    ServerAdmin [email protected]
    ServerAlias www.example.org    # optional
    DocumentRoot htdocs/root
    SSLEngine on
  </VirtualHost>

If you're using Nginx rather than Apache I believe it still requires an external script to handle certificate renewal, but the process remains fairly simple. The same scripts will also work with Apache if you don't want to use mod_md.

[0] https://httpd.apache.org/docs/trunk/mod/mod_md.html