Hierbij nog de bijlage met foutmelding. Dit was niet helemaal goed gegaan denk ik.

What is under the Technical details (Technische details) if you expand this section?

Who is the issuer of the certificate?

You can retrieve the certificate and check details like who issued certificates and expiration dates of certificates.

• Click the link at the bottom of the error page: "I Understand the Risks"
• Let Firefox retrieve the certificate: "Add Exception" -> "Get Certificate"
• Click the "View" button and inspect the certificate and check who is the issuer.

You can see more details like the intermediate certificates that are used in the Details tab.