OPS Center 12.3.3 Proxy Controllers Going Offline

I have noticed on several of our networks that are using OPS Center 12.3.3 to manage our Solaris assets that the Proxy Controller is shown as offline in the Administration section.  This is the case on a stand alone install with a co-located Proxy Controller as well as a larger deployment that has an enterprise controller and 5 remote Proxy Controllers..  I have not been able to get the Proxy back online and I am trying to find some troubleshooting documentation I can use to remedy this as it impacts execution of operations and adding assets that should be managed