Named pipes works but TCP/IP drops connection

Hi all,

I receive the following error from an SSIS connection managers and Management Server intermittently:

A connection was successfully established with the server, but then an error occurred during the login process. (provider: TCP Provider, error: 0 - An existing connection was forcibly closed by the remote host.) (.Net SqlClient Data Provider)

However when using the server name instead of IP address the connection always works and never gets dropped.

That is to say named pipes always works but TCP/IP seems to have a problem.

We need to use TCP/IP as its much faster (load takes 30 minutes when connected with TPC/IP and 4 hours when connected with NP).

As named pipes always works this doesnt seem to be a network issue (unless NP is a lot more resilient than TCP/IP).

Does anyone know how to fix this or at least diagnose what the issue is? Normally the problem is the opposite of this.

Thanks.