My Exchange Server 2013 writes "Error 15021" dozens of times in the Error log. It says, that there is an error using the SSL-Configuration. I googled the error but there seem to be a lot of hits concerning Port 443 but in my case it is Port 444.
netsh http show sslcert
shows some certs (more than needed as far I can tell).
My tries so far:
I checked the bindings and certs in IIS. On Port 444 there is no hostname entered and SNI is not activated as well in contrast to Port 443 (Hostname entered like hostname.domain.com)
The Certs selected are the same. Should I enter the hostname in the Binding on Port 444 as well?
In Windows Exchange Admin center there are multiple Certs but only one is associated with IIS. I am too afraid to delete the ones that seem not to be used.
Any hints?
Thank you in advance.