Hi Matt,
node-ibm_db works only with DB2 client drivers not with unixODBC driver. To use ibm_db against AS400 server you need to get db2connect license file just for IBM Data Server Driver for ODBC and CLI. It is client license file. Alternatively if AS400 server is enabled to accept connection from your particular client i.e. server side licensing is enabled, ibm_db can work. Please work with IBM support to get a license which allows connectivity from "IBM Data Server Driver for ODBC and CLI" to AS400. node-ibm_db internally uses "IBM Data Server Driver for ODBC and CLI" for connectivity.
Thanks and Regards,
Bimal Jha