Cannot connect locally after duckdns

After successfully installing duckdns, my ios app stopped connecting to my local network and only works trough duckdns…

It keeps saying that the SSL cert is invalid and it only verifies if I login over duckdns.

That’s because the SSL certificate is for your duckDNS address, not your IP address. It is working as intended.

If you router has NAT loopback a request to your duckDNS address from inside your network will be redirected by the router to your local address anyway. You can do a traceroute to confirm this.