How to find out what is sending “404 page not found” from my ubuntu server on port 80?
To be clear there is no webserver or docker container running on this port.
Even stranger lsof, ss, netcat doesn’t show processes on port 80 and i m able to run a “server” via sudo nc -l -p 80 locally, what doesn’t affect to “404…” output.

Also there is no redirection via /etc/hosts and i m getting the message via wget, curl or webbrowser locally (root and non-root-user) or from other machines.
A connection via telnet is possible and not show.

Any ideas what i could check?