SecretSync has no logic to handle proxy servers in its code. As a Java application it relies entirely on the Java runtime proxy settings. Information about configuring the proxy for the Java runtime are here:
On startup, SecretSync makes a couple https calls to the below URL.
It does this to exchange your token for an encryption key. It makes no other connections after this point. If it can't connect to the server, the application cannot continue, and will exit.
If your browser uses a proxy, and you put the above URL in your browser and you can connect, you might consider setting the Java runtime to Use browser settings.
Some proxies are 'filtering proxies' which means that they may block (1) certain sites, and (2) certain applications, such as Java from Internet access. This means that simply because your browser can access our site, Java may still not be able to. Because of the many possible configurations and proxy solutions, we can only provide limited support for proxy issues.