Check out the following Citrix support article to solve the Citrix connection error, “Protocol driver error” on a Citrix Presentation Server 4.0 server with two network cards, an application launch fails with Program Neighborhood Client or with Web Interface. It addresses the following Citrix error messages:
“Cannot connect to the Citrix MetaFrame Server. Protocol driver error”.
“Cannot connect to the Citrix MetaFrame server. There is no route to the specified subnet address”
For more information about this error please read the following Citrix Support article: CTX108698 - Error: Protocol driver error... when connecting to a dual-NIC Presentation Server 4.0 Server