@MikeMcQ:
Thank you - that helped me a little bit:
If I call https
curl -I https://ucs.kmvw-io.de/.well-known/acme-challenge/HHIBIWc28HA8J_7-m3jnO65eyVUmLvxc99EzolEV0LA
HTTP/1.1 200 OK
Date: Sat, 05 Feb 2022 16:36:02 GMT
Server: Apache/2.4.25 (Univention)
Strict-Transport-Security: max-age=15552000; includeSubDomains
Last-Modified: Sat, 05 Feb 2022 15:48:10 GMT
ETag: "57-5d7474b58d5a4"
Accept-Ranges: bytes
Content-Length: 87
it works.
If I call http
curl -I http://ucs.kmvw-io.de/.well-known/acme-challenge/HHIBIWc28HA8J_7-m3jnO65eyVUmLvxc99EzolEV0LA
HTTP/1.1 500 Internal Server Error
Date: Sat, 05 Feb 2022 16:34:41 GMT
Server: Apache/2.4.25 (Univention)
Connection: close
Content-Type: text/html; charset=iso-8859-1
I get the error 500.
Now I have to find out, why verification over http does not work anymore. I guess, that anywhere the is hidden a redirection to https.