root@BaseVPS-ubuntu1804-django20:~# curl -v https://15.15.15.15/test
* Trying 15.15.15.15...
* TCP_NODELAY set
* Connected to 15.15.15.15 (15.15.15.15) port 443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* successfully set certificate verify locations:
* CAfile: /etc/ssl/certs/ca-certificates.crt
CApath: /etc/ssl/certs
* TLSv1.2 (OUT), TLS handshake, Client hello (1):
* TLSv1.2 (IN), TLS handshake, Server hello (2):
* TLSv1.2 (IN), TLS handshake, Certificate (11):
* TLSv1.2 (OUT), TLS alert, Server hello (2):
* SSL certificate problem: self signed certificate
* Closing connection 0
curl: (60) SSL certificate problem: self signed certificate
More details here: https://curl.haxx.se/docs/sslcerts.html

curl failed to verify the legitimacy of the server and therefore could not
establish a secure connection to it. To learn more about this situation and
how to fix it, please visit the web page mentioned above.

root@BaseVPS-ubuntu1804-django20:~# tail -F /var/log/nginx/error.log
2018/09/05 13:41:02 [crit] 3975#3975: *38 SSL_do_handshake() failed (SSL: error:1417D102:SSL routines:tls_process_client_hello:unsupported protocol) while SSL handshaking, client: 221.212.99.106, server: 0.0.0.0:443
2018/09/05 13:41:03 [crit] 3975#3975: *39 SSL_do_handshake() failed (SSL: error:1417D18C:SSL routines:tls_process_client_hello:version too low) while SSL handshaking, client: 221.212.99.106, server: 0.0.0.0:443
2018/09/05 16:19:31 [crit] 3975#3975: *48 SSL_do_handshake() failed (SSL: error:1417D18C:SSL routines:tls_process_client_hello:version too low) while SSL handshaking, client: 198.108.66.16, server: 0.0.0.0:443
2018/09/05 18:20:12 [error] 3975#3975: *52 connect() to unix:/run/gunicorn.sock failed (111: Connection refused) while connecting to upstream, client: 139.162.116.133, server: 15.15.15.15, request: "GET / HTTP/1.1", upstream: "http://unix:/run/gunicorn.sock:/", host: "15.15.15.15"
2018/09/05 19:45:39 [crit] 3975#3975: *56 SSL_do_handshake() failed (SSL: error:1417D102:SSL routines:tls_process_client_hello:unsupported protocol) while SSL handshaking, client: 80.82.70.118, server: 0.0.0.0:443