When you ssh into OL 7, there might be quit a delay before you see the shell prompt after entering your password.
The following is one way to fix the issue:
# cp /etc/ssh/sshd_config /etc/ssh/sshd_config.orig
# sed -i "s/#UseDNS yes/UseDNS no/" /etc/ssh/sshd_config
# systemctl restart sshd.service
The other way would be to make sure your configured DNS server provides a reverse DNS lookup of your client IP address.