1. Visit the URL http://<your_domain>:8880 or https://<your_domain>:8443 (For SSL) and login.
2. Click on Tools & Settings from the left menu.
3. Now click on IP address banning(failban) under Security section.
4. Now you can see blocked IP addresses under the Banned IP Addresses tab.
5. Mark the checkbox of the specific IP address and click on Unban button.