Connect to SAP gateway failed inconsistencies

We have a web server that connects using the .net connector (1.x) to a couple of R/3 servers. R/3 server L has a single client installed and all versions of the connector can work with it. R/3 server I has multiple clients and can only be reached by an older version of the connector (Visual Studio 2002 .net). The newer connectors were working fine until a few days ago. Since the older apps can connect to the same R/3 server ok, I don't think its a connectivity issue.

Anyone have any ideas?