After nginx & certbot configuration I can't access strapi through https://domain.com:1337 but i can through http://[DigitalOcean IP]:1337

Keep in mind that Nginx only controls whats being passed on ports 80 and 443. Anything on port 1337 is Strapi directly, hence why https://api.eduardstefan.com:1337 as Nginx doesn’t manage that.