...
#ssl_certificate /etc/ssl/mydomain.crt;
#ssl_certificate_key /etc/ssl/private/mydomain.key;
ssl_certificate /etc/letsencrypt/live/mydomain.ru/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/mydomain.ru/privkey.pem;
ssl_trusted_certificate /etc/letsencrypt/live/mydomain.ru/chain.pem;