One to watch out for since the introduction of Horizon View 6.1 VMware have introduced a new port for JMS TCP/4002 Horizon 6.1 Documentation

Also be aware before enabling enhanced mode…

If you plan to change an upgraded View environment from Enabled to Enhanced, you must first upgrade all View Connection Server instances, security servers, and View desktops to Horizon 6 version 6.1 or a later release. After you change the setting to Enhanced, the new setting takes place in stages.
1
You must manually restart the VMware Horizon View Message Bus Component service on all View Connection Server hosts in the pod, or restart the View Connection Server instances.
2
After the services are restarted, the View Connection Server instances reconfigure the message security mode on all desktops and security servers, changing the mode to Enhanced.
3
To monitor the progress in View Administrator, go to View Configuration > Global Settings.
On the Security tab, the Enhanced Security Status item will show Enhanced when all components have made the transition to Enhanced mode.
Alternatively, you can use the vdmutil command-line utility to monitor progress. See Using the vdmutil Utility to Configure the JMS Message Security Mode.
View components that predate Horizon 6 version 6.1 cannot communicate with a View Connection Server 6.1 instance that uses Enhanced mode