We are also seeing this issue with the latest vCO appliance (5.5.1.0 Build 1617225). It happens when using the downloadable client as well as the web-based client (JNLP). We are using all of the default ports with SSO authentication to vCenter and all of the firewall rules look correct. Here's the Java console output I get when using the JNLP client:
2014-04-04 19:21:36.665-0400 INFO [CertTrackerMain] Can not find keystore C:\Program Files (x86)\Java\jre7\lib\security\jssecacerts
2014-04-04 19:21:36.717-0400 INFO [Application] Loading properties at : C:\Users\shane\Downloads\.\vmo.properties ...
2014-04-04 19:21:36.718-0400 INFO [Application] No properties found !
2014-04-04 19:21:36.718-0400 INFO [Application] Loading ...
2014-04-04 19:21:36.856-0400 INFO [Application] Starting...
2014-04-04 19:21:36.858-0400 DEBUG [Preferences] Loading preferences from C:\Users\shane\.vmware\vmware-vmo.cfg ...
2014-04-04 19:21:36.859-0400 INFO [Preferences] Loaded preferences file: C:\Users\shane\.vmware\vmware-vmo.cfg
2014-04-04 19:21:43.329-0400 DEBUG [VSOFactoryClient] Start connection to VMO server : chopin.esx.gatech.edu:8281
2014-04-04 19:21:43.330-0400 DEBUG [VSOFactoryClient] Create Session
2014-04-04 19:21:45.189-0400 DEBUG [TypeConverter] Convertor Re registration of type : Array
2014-04-04 19:21:45.216-0400 DEBUG [VSOFactoryClient] Session created
2014-04-04 19:21:55.447-0400 ERROR [VSOFactoryClient] javax.jms.JMSException: Failed to create session factory
2014-04-04 19:21:55.452-0400 DEBUG [VSOFactoryClient] javax.jms.JMSException: Failed to create session factory
ch.dunes.util.DunesServerException: javax.jms.JMSException: Failed to create session factory
at ch.dunes.model.client.InVMJmsClient.createConnection(InVMJmsClient.java:118)
at ch.dunes.model.client.VCOHornetQJMSClient.connectTopics(VCOHornetQJMSClient.java:79)
at ch.dunes.model.client.VSOFactoryClient.connect(VSOFactoryClient.java:314)
at ch.dunes.model.client.VSOFactoryClient.connect(VSOFactoryClient.java:272)
at ch.dunes.vso.app.VSOClientAuthService.login(VSOClientAuthService.java:45)
at ch.dunes.vso.app.VSOClientAuthService.login(VSOClientAuthService.java:60)
at ch.dunes.vso.app.VSOLoginDialog._doLogin(VSOLoginDialog.java:486)
at ch.dunes.vso.app.VSOLoginDialog.access$400(VSOLoginDialog.java:52)
at ch.dunes.vso.app.VSOLoginDialog$10.run(VSOLoginDialog.java:464)
at java.lang.Thread.run(Unknown Source)
Caused by: javax.jms.JMSException: Failed to create session factory
at org.hornetq.jms.client.HornetQConnectionFactory.createConnectionInternal(HornetQConnectionFactory.java:615)
at org.hornetq.jms.client.HornetQConnectionFactory.createTopicConnection(HornetQConnectionFactory.java:145)
at ch.dunes.model.client.InVMJmsClient.createConnection(InVMJmsClient.java:110)
... 9 more
Caused by: HornetQException[errorCode=2 message=Cannot connect to server(s). Tried with all available servers.]
at org.hornetq.core.client.impl.ServerLocatorImpl.createSessionFactory(ServerLocatorImpl.java:619)
at org.hornetq.jms.client.HornetQConnectionFactory.createConnectionInternal(HornetQConnectionFactory.java:611)
... 11 more