Mixed Content with root path

Apps & Services myopenHAB
1

On myopenhab.org I logged to my openhab. One page “Auto” contains webframecard with source url in format /page/page_xxxx
On-site page with this content works fine, content is displayed and works.
On myopenhab I get mixed content error in browser. Page works, but webframecard is empty. Service rewrite link from https into http and browser dont accept this.

Mixed Content: The page at ‘https://home.myopenhab.org/page/Auto’ was loaded over HTTPS, but requested an insecure frame ‘http://home.myopenhab.org:443/page/page_xxxx/’. This request has been blocked; the content must be served over HTTPS.

Is there a solution?

2

Looks a bit strange. While protocol is http port that is being used in 443. Seems to be a contradiction.
What is the source/yaml code of the relevant part ?

3

Part from page Auto:

       - component: oh-grid-row
          config: {}
          slots:
            default:
              - component: oh-grid-col
                config:
                  width: "50"
                slots:
                  default:
                    - component: oh-image-card
                      config:
                        url: https://media.volkswagen.com/Vilma/....9cff.png
              - component: oh-grid-col
                config:
                  width: "50"
                slots:
                  default:
                    - component: oh-webframe-card
                      config:
                        src: /page/page_023cbac01c
                        height: 430