We have a wcf pub/sub setup using reliable sessions via netTcpBinding and on one machine where both the publication service and subscription service are being hosted in a co
Ok, I found out what my problem was.
The service the client application was connecting to had mxConnection of 10. We were also using SecureMessaging and had a listenBacklog of 1. Amended maxConnections to 100 and listBacklog to 200 and it all works fine.
For me the problem was that I didn't have the right Service Reference (from a dev machine vs a production machine).