Certification problems..dns problem?

Yep, I see: Now you have a new certificate, created today.

https://transparencyreport.google.com/https/certificates?cert_search_auth=&cert_search_cert=&cert_search=include_expired:false;include_subdomains:false;domain:www.onderwegnaarmorgen.com&lu=cert_search

So to renew the certificate, open your router, close it when done.