@bobbyiliev Thanks for your reply!

First file:

server {
    listen 80;
    listen [::]:80;

    server_name 167.71.12.224 www.lavrikroman.net lavrikroman.net;
    include /etc/nginx/snippets/letsencrypt-acme-challenge.conf;


    location = /favicon.ico { access_log off; log_not_found off; }
    location /static/ {
        root /home/roma/blog/backend/;
    }

    location / {
        include proxy_params;
        proxy_pass http://unix:/home/roma/gunicorn.sock;
    }
}

Default file:

   server {
        server_name www.lavrikroman.net;   
        index index.html index.htm index.nginx-debian.html;

        location / {
                # First attempt to serve request as file, then
                # as directory, then fall back to displaying a 404.
                try_files $uri $uri/ /index.html;
        }

    #listen [::]:443 ssl ipv6only=on; # managed by Certbot
    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/www.lavrikroman.net/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/www.lavrikroman.net/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot

}