Why you need to Restart SSH Service
As root System Administrators its one of the common tasks you need to be done on live servers is restarting services.If you change ssh configuration file (for example you change the SSH port number) this modification require a restart to take effect.
How To Restart SSH Service under Linux / UNIX
For CentOS / RHEL / Fedora / Redhat Linux Restart SSH
service sshd restart
Or
/etc/init.d/sshd restart
Restart SSH On RHEL/CentOS/Fedora Linux with systemd
sudo systemctl restart sshd
Restart SSH On Debian / Ubuntu Linux
/etc/init.d/ssh restart
Or
service ssh restart
Or
sudo service ssh restart
Restart SSH On Debian/Ubuntu/Mint Linux with systemd
sudo systemctl restart ssh
Restart SSH On For FreeBSD
/etc/rc.d/sshd restart
Or
sudo service sshd restart
Restart SSH For OpenBSD
/etc/rc.d/sshd restart
Or
doas /etc/rc.d/sshd restart