Multiple Node.js apps on NginX resolve to wrong subdomain

I’m fairly new here, so bear with me.

I just created a Ubuntu 14.0.4 droplet and installed NginX and Node.js. Two domains are configured with the D.O. nameservers, and two DNS entries are added on D.O.

$ORIGIN domain1.com.
$TTL 1800
domain1.com. IN SOA ns1.digitalocean.com. hostmaster.domain1.com. xxxxxxxxxx xxxxx xxxx xxxxxx xxxx
domain1.com. 1800 IN NS ns1.digitalocean.com.
domain1.com. 1800 IN NS ns2.digitalocean.com.
domain1.com. 1800 IN NS ns3.digitalocean.com.
domain1.com. 1800 IN A 1.2.3.4
*.domain1.com. 1800 IN CNAME domain1.com.

$ORIGIN domain2.com.
$TTL 1800
domain2.com. IN SOA ns1.digitalocean.com. hostmaster.domain2.com. xxxxxxxxxx xxxxx xxxx xxxxxx xxxx
domain2.com. 1800 IN NS ns1.digitalocean.com.
domain2.com. 1800 IN NS ns2.digitalocean.com.
domain2.com. 1800 IN NS ns3.digitalocean.com.
domain2.com. 1800 IN A 1.2.3.4
*.domain2.com. 1800 IN CNAME domain2.com.

Both domains have the * => @ CNAME wildcard.

On NginX there are two files (one for every domain) on sites-enabled (and of course sites-available): domain1.com

upstream app_domain1 {
        server 127.0.0.1:3000;
}
server {
        listen 80;
        server_name domain1.com;
        access_log /var/log/nginx/domain1.log;
        location / {
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection "upgrade";
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header Host $http_host;
                proxy_set_header X-NginX-Proxy true;
                proxy_pass http://app_domain1;
                proxy_redirect off;
        }
}

domain2.com

upstream app_domain2 {
        server 127.0.0.1:4000;
}
server {
        listen 80;
        server_name domain2.com;
        access_log /var/log/nginx/domain2.log;
        location / {
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection "upgrade";
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header Host $http_host;
                proxy_set_header X-NginX-Proxy true;
                proxy_pass http://app_domain2;
                proxy_redirect off;
        }
}

Two simple app.js files with some “Hello World!” responses run with forever, listening on port 3000 & 4000 as stated in the upstream part of above NginX files.

When i browse to domain1.com or domain2.com, i get the response i would expect. When i browse to www.domain2.com (the second domain) it’s also the correct response.

But when i browse to www.domain1.com, i get the response of domain2.com.

What am i doing wrong?