Discourse-Zertifikat abgelaufen

[Canapin (Coin-coin le Canapin)]

Yes, the explanation was here:

Let's Encrypt certificate doesn't automatically renew, but rebuilding does trigger the renewal

I recently worked on the le cert renewal. It is the http to https redirect - acme does not handle being told to redirect well at all and by default attempts to connect on the same protocol (http) as it did when it was setup initially Recent updates to the let’s encrypt template should fix these renewals going forward.