We found the issue.
It appears that something changed in the RFC library included with patch 9, and now an entry in the services file is needed for sapgw<nn>s (<nn> = SAP system number). For example, sapgw00s 4800/tcp would be used if system number is 00.
We are using an RFC Server and connecting to it using SNC, so this services entry needs to be defined. We are confused as to why/how our code was working with patch 8 or older versions of the RFC library without the services entry.
Thanks
Tim