Strange "certificate verify failed"

[LLyaudet]

Hello,

I'm testing the links on one page of my website here:
https://lyaudet.eu/laurent/index.html

It fails to check the following link:

  Line: 150 https://genealogy.math.ndsu.nodak.edu/id.php?id=158175
  Status: 500 Can't connect to genealogy.math.ndsu.nodak.edu:443 (certificate verify failed)

  This is a server side problem. Check the URI. 

This link perfectly works with https in Firefox and in Chrome.
No redirect, no certificate warning.
I don't know what is wrong with it.

Let me know if I can do something else.

Best regards,
Laurent Lyaudet

[LLyaudet]

Same problem:
https://lyaudet.eu/laurent/publications.html

It fails to check the following link:

    Line: 98 https://scanr.enseignementsup-recherche.gouv.fr/person/idref123332206
    Status: 500 Can't connect to scanr.enseignementsup-recherche.gouv.fr:443 (certificate verify failed)

    This is a server side problem. Check the URI.