Duplicati login error on HASS panel when access duckdns URL

When I use DuckDNS domain to access HASS, the iframe duplicati is getting this error:

My configuration file:

panel_iframe:
  duplicati:
    title: "Duplicati"
    url: "http://192.168.1.8:8200"
    icon: mdi:backup-restore
    require_admin: true

When I use internal IP to access HASS. Everything works fine.
Does anyone know how to fix it?

My HASS core: 2022.5.0
I’m using HASS Container on RaspberryPi, and access to DuckDNS domain from the same network (wifi).

Sorry because I dont know where category to put this topic.