Having issue the Windchill ("Unable to invoke remote method")

We are having issue running any page, which require Java. Though the page is appearing, some functionalities in the page are not working and the page throws error after a while. Following is the error we're getting. Any help ?

 wt.util.WTRemoteException: Unable to invoke remote method; nested exception is: wt.util.WTRemoteException: Unable to locate method server; nested exception is:
 wt.util.WTRemoteException: Unable to locate method server; nested exception is:
 wt.util.WTRemoteException: Unable to get server; nested exception is:
 wt.util.WTRemoteException: Unable to locate server manager; nested exception is:
 java.rmi.ConnectException: Connection refused to host: adtwtipwvsds01.tawazun.ae; nested exception is: 
 java.net.ConnectException: Connection timed out: connect
Nested exception is: wt.util.WTRemoteException: Unable to invoke remote method
Nested exception is: wt.util.WTRemoteException: Unable to locate method server
Nested exception is: wt.util.WTRemoteException: Unable to locate method server
Nested exception is: wt.util.WTRemoteException: Unable to get server
Nested exception is: wt.util.WTRemoteException: Unable to locate server manager
Nested exception is: java.rmi.ConnectException: Connection refused to host: adtwtipwvsds01.tawazun.ae; nested exception is: 
 java.net.ConnectException: Connection timed out: connect

All client machines are having Java x86 1.7 Update 60.

Thank you