Certificate expired in https://vinayaka.tsia.de.
I just checked that and the certificate is valid here.
Looks like it has been renewed so the problem is solved.
vinayaka.tsia.de seems still to have an expired certificate. I reopen this issue.
I checked it again on another device and the certificate works fine here,too.
I'll try to get in touch with the admin of the website.
Maybe he knows better what's wrong here.