Please follow the steps below on troubleshooting "Unable to connect to Cluster" error.
Confirm Connectivity Between AutomationFX Server and CUCM.
- Ping CUCM Server form MigrationFX Server
- Telnet to the specific port in CUCM used by MigrationFX Server
Ensure the user account used to add the cluster has Appropriate Permissions assigned according to the AutomationFX Documentation.
NOTE: Admin User and Admin User Password matches with CUCM (Both User Name and Password should be in exact case as CUCM)
A recent Windows Update for Windows 7, 8, Server 2008R2 & 2012R2 (KB3161639) has broken SSL/HTTPS connectivity to certain Apache/Tomcat web servers (CUCM, UCCX). This issue is caused by the addition of two new Chiper Suites "TLS_DHE_RSA_WITH_AES_128_CBC_SHA & TLS_DHE_RSA_WITH_AES_256_CBC_SHA"
Please (check/remove) these updates and try again
KB3161639(Note: KB3161608 contains KB3161639 optional update), The other options are to remove KB3161608 or KB3161606.
NOTE: You May need To Restart the PC/Server for the changes to take effect.
See following links for more details on the error and options on how to fix:
Addition to this Microsoft just published new patches in its place, there are a pair of new patches, KB 3172605 for Windows 7, and KB 3172614 for Windows 8.1, if you can try applying those patches it should resolve the issue.