Why do I receive nginx http headers when I use Apache? (Synology NAS)

Maybe this belongs on a Synology forum, but maybe NC has something to do with it or someone here encountered something similar while installing NC on their NAS. I sometimes get nginx error messages and at all times, all the http headers are from nginx, but web station has only been configured to use Apache. I don’t know where to find Apache error logs despite searching. The nginx log file I found didn’t show anything interesting.

Thank you if you have any idea or tip to find useful logs.