I’m seeing something odd when looking at this host with the host command.
$ host mongo-ldn.innovatete.ch
mongo-ldn.innovatete.ch has address 178.79.176.33
mongo-ldn.innovatete.ch has IPv6 address 2a01:7e00::f03c:91ff:fe08:a3ac
;; connection timed out; no servers could be reached
I’m not accustomed to seeing some data come back followed by a timeout, and I don’t know offhand what causes that technically. Do you have a Unix machine where you can run host and see if you see the same result? If so, this must have something to do with why the CA can’t manage to complete the DNS resolution either.