To unblock an IP from the server, first log into your Nine Planets account, then from the Support menu select the Unblock IP Address option.
The next page will automatically fill the field with the IP of the computer you're connect with; you can unblock that, or type in a different IP if needed. Then just click the Check for IP Block and Remove button. It will check for and remove any blocks for that IP, or let you know if no blocks were found.