Whenever you made a change to /etc/ssh/sshd_config you must restart the SSHD or make it reload its configuration by typing:

or

You can do this with a running SSH connection and you don't need to log out. But the changes will only take effect for each user the next time they try to log in.

OR

systemctl status sshd

systemctl start sshd
systemctl stop sshd
systemctl restart sshd