Why am I unable to access my website after installing an SSL certificate using Certbot? (running Ubuntu and Nginx)

I can not establish a connection to port 443 on my nginx server.

I needed port 443 to enable https connections, I used certbot to install an ssl certificate, and I went with the default installation, and default instructions in this guide

Even though I've set the 'nginx full' command to open both http and https ports, I double checked to make sure that port 443 is really open by running the following command sudo lsof -i -P -n | grep LISTEN, and in the response, I got port 443 as being used by nginx

I tried tools like cURL to test my ports, port 80 works just fine, but I get no response from port 443

I lack experience with server administration and I tried to check other resources but I don't know what else to do.

my sites-available configuration:

server {

        root /var/www/muhammed-aldulaimi.com/html;
        index index.html index.htm index.nginx-debian.html;

        server_name muhammed-aldulaimi.com www.muhammed-aldulaimi.com;

        location / {
                try_files $uri $uri/ =404;
        }

    listen [::]:443 ssl ipv6only=on; # managed by Certbot
    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/muhammed-aldulaimi.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/muhammed-aldulaimi.com/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


}
server {
    if ($host = www.muhammed-aldulaimi.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


    if ($host = muhammed-aldulaimi.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


        listen 80;
        listen [::]:80;

        server_name muhammed-aldulaimi.com www.muhammed-aldulaimi.com;
    return 404; # managed by Certbot

}

ufw status:

22/tcp                     ALLOW       Anywhere
Nginx Full                 ALLOW       Anywhere
22/tcp (v6)                ALLOW       Anywhere (v6)
Nginx Full (v6)            ALLOW       Anywhere (v6)

Solution 1:

After verifying that there was no issue in ubuntu's firewall settings, I assumed that the issue lied in the web host itself. I was using AWS Lightsail, and turned out that Lightsail only accepted connections coming from port 22 and 80. Adding a rule that accepted other ports in the Networking tab; solved my issue.