NAT can't find external subprogram after Natural upgrade

We were successfully calling an external web service from Natural 3.1.5 but when we went to version 4.1.4 SP8 of Natural we now get a 6972 R4 (No server found in service directory for the subprogram/library whose names are indicated in the error message) or a 6971 R1 (no Transport layer) error. No changes were made to the Natural code or to the javaxmlrpcserver artifacts.

We are using EXX with NATRPC version and SYSIDL

Did something change in Natural that we lost some kind of connection?
Has anyone had this experience?

Thanks in advance,

Did your SYSRPC/SM entries come forward (NATCLTGS)? Are you able to PIng the Broker from SYSRPC/XC?