DB2 linked service error with selfhosted IR

Trying to connect to a DB2 source via an selfhosted IR. DB2 is v. 11.5 and from the documentation it should be supported. However we are running into the following error

Have not received expected codepoint: EUSRIDNWPWD. SQLSTATE=HY000 SQLCODE=-1040

Facts:
- Running IR v5.17.8154.2
- DB2 server version is v11.5
- DB running on non-standard port -> 30214
- Can successfully connect to the DB2 server via telnet from the IR machine
- Can successfully connect to the DB2 server via DBVisualizer (using JDBC) from the IR machine
- Tried installing IBM drivers v11.1, v11.5 and v11.5.4 respectively prior to installing IR.
- Also tried using a ODBC linked service to DB2, with no luck.
- Tried to spin up a DB2 instance locally on our network and ADF seems to connect fine via IR. Local instance does not require SSL and otherwise using vanilla configuration.

Any idea what is going wrong here?