nginx: Exclude subdomains from being SSL-encrypted

Can you exclude all other subdomains from being encrypted if the main site url is using SSL?

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

    server_name .example.com;
    return 301 https://$host$request_uri;
}
server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;

    ## ssl stuff

    server_name www.example.com;
    return 301 https://example.com$request_uri;
}
server {
    listen 443 ssl default_server http2;
    listen [::]:443 ssl http2;
    server_name example.com;
    root /home/forge/example.com/public;
    index index.html index.htm index.php;
    charset utf-8;   
}

Solution 1:

Define a more specific server, that will be used in place of the one you have.

server {
  listen 80;
  server_name subdomain1.example.com; # add others if you like
  root /home/forge/example.com/public/subdomain; # check this
  index index.html index.htm index.php;
}

As ceejay noted in comments there's no redirect included in the config you included, so something else is going on.

1. exact name
2. longest wildcard name starting with an asterisk, e.g. “*.example.org”
3. longest wildcard name ending with an asterisk, e.g. “mail.*”
4. first matching regular expression (in order of appearance in a configuration file)