Configuration page mangled when remotely accessing via domain
Hello, i'm facing an issue when i'm trying to access my router's configuration page remotely. The page works fine if i access it from LAN using either my LAN IP or WAN IP and it works if i access it from outside the local network via WAN IP.
The problem is that i am behind a dynamic WAN IP and have to use DDNS. If i access it through my DuckDNS domain (or my actual domain that points to DuckDNS), the page that loads is broken. This happens both from my LAN via my set port 60000 or from outside via 60006.
Browsers and devices i have tested are Windows 10 Chrome (this local PC), Ubuntu Firefox (my home server) and Android Chrome (my Nokia 8 phone), no difference.
Is this an issue with my router or something else? I can access all of the functions in my home server fine via the domains and it's only the router config page that fails to work.
Screenshot of the broken page contents below.