You can try referring the multiple jar files as list to  gateway.

Set AssemblyFileNameWithPath1="jar path 1" 

Set AssemblyFileNameWithPath2="jar path 2"
 Set gateway=##class(%Net.Remote.Gateway).%New()
 Set classpath=##class(%ListOfDataTypes).%New()
  Do classpath.Insert(AssemblyFileNameWithPath1)

Do classpath.Insert(AssemblyFileNameWithPath2)
 Set status=gateway.%Connect(Host,Port,NameSpace,10,classpath)

I tried your quey and it ran successfully.

SELECT * FROM Config.IO WHERE ID IN ('1||1||9852553062' , '1||1||9852553061' ) order by 1 desc

The error you got seems very generic. Kindly check the table again.

The SQLCODE -400 error “Fatal error occurred” is a general error. It is generated when a more specific SQLCODE error code is not available.