From the article :
When changing the port that sshd listens on , if SELinux is enabled, then you must run semanage to allow sshd to run on that new port.
For example. if you have changed sshd to listen on port 2222 , then you must [type the following command to change port to allow sshd to run on port 2222.
semanage port -a -t ssh_port_t -p tcp 2222
systemctl restart sshd`
If the port is already assigned in semanage , then you need to use -m instead of -a in your semanage command.
Otherwise semanage says “port already assigned” and when you restart sshd it fails.
Here is a screenshot from my linux server: