Hi, I’'ve just tried Spark to connect to an external jabber server (jabber.ru, for example), and have problems with getting through our corporate proxy server.
If that is true about the proxy settings for spark, you may have an issue. Most properly configured networks that use a proxy configure all network traffic to go through them.
Have you tried to telnet to the port or run a port scan of the address. Your company could be blocking XMPP transports. My previous company blocked all IM traffic except our own internal server.
Well that then verifies that the proxy settings of spark do not work for the XMPP connection. Your PSI connection proves that proxy authentication is needed for your network to allow the transport and that Spark does not do it.