"The server could not be reached" error is thrown when users try logging into Spotfire client via Citrix

"The server could not be reached" error is thrown when users try logging into Spotfire client via Citrix

When users / administrators try to login to a Spotfire client that has been published via Citrix, they run into the following error:

 "The server could not be reached"

The following is the stack trace that can be seen when this error is thrown:
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Stack Trace:

   at Spotfire.Dxp.Services.WebServiceBase`1.InvokeService[T](ServiceMethod`1 serviceMethod, ExceptionFactoryMethod exceptionFactoryMethod)   at Spotfire.Dxp.Services.Authenticator.Authenticate(SpotfireIdentity identity, PrincipalProvider provider)   at Spotfire.Dxp.Loader.LoginHandler.PerformLogin()

WebException at Spotfire.Dxp.Framework:
The remote server returned an error: (401) Unauthorized . (HRESULT: 80131509)
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Note that when the Administrator tries to login to a Spotfire client on the Citrix machine, the analyst client works fine.