Problem installing wordpress on subdomain (nginx / ubuntu)

Hi,

I’ve been trying to configure my single droplet to host two different website on two different domain, where one of them is a subdomain:

1. My homepages (static - home/about/contact etc)
2. Blog (Dynamic - Wordpress)

I’m using Nginx and have the following config files

Main - example.com

server {
        listen 443 default_server;
        listen [::]:443 default_server;

        root /var/www/example.com.au;
        index index.html;

        ssl on;
        ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
        ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;


        server_name example.com www.example.com;
        location / {     try_files $uri $uri/ =404;
 }
 }

server {
       listen 0.0.0.0:80;
       server_name example.com www.example.com;
       rewrite ^ https://$host$request_uri? permanent;
}

Subdomain - blog.example.com

server {
listen 80;
listen [::]:80;
server_name blog.example.com www.blog.example.com;
return 301 https://blog.example.com$request_uri;

root /var/www/blog.example.com;

index index.php index.html index.htm;

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

location ~ \.php$ {
include snippets/fastcgi-php.conf;
fastcgi_pass unix:/run/php/php7.0-fpm.sock;
}

location ~ /\.ht {
deny all;
}

location = /favicon.ico { log_not_found off; access_log off; }
location = /robots.txt { log_not_found off; access_log off; allow all; }
location ~* \.(css|gif|ico|jpeg|jpg|js|png)$ {
expires max;
log_not_found off;
}

The main site is working, but when I try to access the sub domain I get greeted by an error message saying that “blog.example.com’s server DNS address could not be found”.

I can Ping and nslookup the server using the subdomain address (blog.example.com) and it returns the IP-address of my server.

I suspect that I’ve done something wrong with my DNS records but I can’t figure out what that might be. I’ve set up CNAME records, A records, and Wildcard records(*.example.com) for my subdomain.

Has anybody had this problem and if so, how were you able to resolve it?

Thanks!