May have found the issue but not the solution.
The query below is a passthrough to Intersystems Cache database via ODBC
"SELECT * FROM wmhISTORYdETAIL" runs as a passthrough without asking for the DNS (no issue)
'SELECT WMHistoryDetail.HistDate, WMHistoryDetail.HistMovDate, WMHistoryDetail.HistMovType, WMHistoryDetail.HistLocnFrom, WMHistoryDetail.HistLocnTo,WMHistoryDetail.HistHMNumber from SQLUser.WMHistoryDetail'
always asks for the DNS but both are linked to a table that has the password saved.
Any Ideas please?