Clients can attack the SSL server by sending many renegotiation (SSL handshake) requests to it. This can overwhelm the server and it might go down. To prevent such attacks, you can enable DOS attack protection.
To enable SSL renegotiation DOS attack protection:
In the <Installation Path>/config/unifi.xml file, edit the following line:
<SSL reneg_dos_protection="0"/>
reneg_dos_protection: Set the value to 1 to enable DOS attack protection. The default value is 0.
Save the file.