The ProxySG appliance event log contains many entries about HTTPS management connection failures such as:
SGOS 6.5 introduced advanced logging for TLS connection attempts to the ProxySG Management Console. These messages are logged whenever a remote device attempts a connection to the management port of the HTTPS console, but does not succeed in setting up a TLS session. Examples might be automated scripts or monitoring software that may be deployed to periodically create TCP connections to the ProxySG management port, but do not proceed with a full TLS session. This would cause the messages to be logged.
The message contains the IP address of the remote system attempting to access the ProxySG appliance. Check these devices to see why they are initiating connections to the management port and if they should be generating full TLS connections. Note that these messages may be generated legitimately on occasion (for example, if an administrator fails to launch the Java applet of the Management Console due to Java security settings or simply cancelling the dialog, this results in several entries being logged).