Konstantopoulos,Good to hear. For future reference, firewall and proxy requirements for Spark are documented here ongoing:Cisco Spark | Firewall and Network Requirements for th...Dave

Your assessment is correct.  To be clear, what's going on is that the non-browser Spark clients have implemented certificate pinning  as a security measure to prevent a man-in-the-middle attack .Because disabling pinning would leave us vulnerable sec...