Look into NAT hairpinning on your router/firewall and see if you can use the external ip. :)

What is the status code of that page? Is it actually an empty response, or does it just look blank in a browser?

When you access it from the internet, do you use an ip and port or a domain name? My first guess is that you entered the domain name somewhere in the config of either Opencloud or a reverse proxy, and the mismatch (between the expected domain name and the ip address used instead) is what causes trouble.

Check OC_CORS_ALLOW_ORIGINS and WEB_CORS_ALLOW_ORIGINS

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:

[Thread #262 for this comm, first seen 29th Apr 2026, 13:40] [FAQ] [Full list] [Contact] [Source code]

Open config.php and look for the entry named trusted_domains. Make sure it contains both the domain name and the local IP address:

'trusted_domains' => array(
    0 => 'nextcloud.your.domain',         // the public FQDN
    1 => '172.22.?.?',                    // the local IP address
    2 => '...',                           // other addresses, like if you're using a VPN
),

If the web app is opened using an address or DNS name that isn't included in this list, the browser will connect, but the app will refuse to work.

Nevermind, I completely overlooked that the service is Opencloud, not Nextcloud. Nevertheless, you should investigate whether Opencloud has an equivalent config variable.