Hello, Running Debian Stretch here.
I modified /etc/security/limits.conf with limits for soft/hard nofile to 10000 for * (any user), root and my username. Also added session requried to /etc/pam.d/common-session* files. Only for root ulimit -Hn or -Sn shown the correct number. For my username it did not work until I edited /etc/systemd/user.conf and /etc/systemd/system.conf with the number of max open files I am willing to allow for this user. Is this a bug or expected behavior? Why doesn't it work from editing /etc/security/limits.conf? Thank you.