When the encryption method is set to 3DES only, Internet Explorer / Chrome is not able to open the SNX Portal page causing the SSL handshake to fail.
Issue might occur after installing Microsoft Update KB2585542.
Enable RC4 (or AES on newer versions) as an optional encryption algorithm for SSL Network Extender (SNX):
- In SmartDashboard, go to "Policy" menu - click on "Global Properties...".
- Open "Remote Access" - go to "SSL Network Extender".
- In the "Encryption" section, in the "Supported encryption methods" field, select either "3DES, RC4" or "AES, 3DES, RC4" (depends on the version).
- Click on OK to apply the changes.
- Install the policy on the involved Security Gateway.