Sub Siteyi Nasıl SSL Destekli Yapabilirim Let's Encrypt

default.conf'un tamamını atabilirmisiniz?

#server {
# listen 80;
# server_name localhost;

#charset koi8-r;
#access_log /var/log/nginx/host.access.log main;

# location / {
# root /usr/share/nginx/html;
# index index.html index.htm;
# }

#error_page 404 /404.html;

# redirect server error pages to the static page /50x.html
#
# error_page 500 502 503 504 /50x.html;
# location = /50x.html {
# root /usr/share/nginx/html;
# }

# proxy the PHP scripts to Apache listening on 127.0.0.1:80
#
#location ~ \.php$ {
# proxy_pass http://127.0.0.1;
#}

# pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
#
#location ~ \.php$ {
# root html;
# fastcgi_pass 127.0.0.1:9000;
# fastcgi_index index.php;
# fastcgi_param SCRIPT_FILENAME /scripts$fastcgi_script_name;
# include fastcgi_params;
#}
# deny access to .htaccess files, if Apache's document root
# concurs with nginx's one
#
#location ~ /\.ht {
# deny all;
#}
#}

server {
listen 443 ssl http2;
server_name irc.haydisohbet.net;
ssl_certificate /etc/letsencrypt/live/irc.haydisohbet.net/cert.pem;
ssl_certificate_key /etc/letsencrypt/live/irc.haydisohbet.net/privkey.pem;
access_log /var/log/nginx/irc.haydisohbet.net.access.log;
error_log /var/log/nginx/irc.haydisohbet.net.error.log warn;

location / {
proxy_pass "http://127.0.0.1:9090/";
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-Forwarded-Port $server_port;

}
}

server {
listen 80;
server_name irc.haydisohbet.net;
return 301 https://irc.haydisohbet.net$request_uri;
}

Kullandığınız irc yazılımı ile ilgili olabilir. Bilemiyorum.