hints for remote database

In our ETL processing we have inserts with selects form remote databases. The select part is too slow and therefore I am trying to use hints.

What I already found out:

select /*+ opt_param('optimizer_index_cost_adj' 1) */ col_id from tab1@to_db where col2 = 3 -> using index on col2

select /*+ opt_param('optimizer_index_cost_adj' 1) */ col_id from tab1@to_db where col2 = 3 -> FTS

so, witt simple selects the hints are taken into consideartin for the executino plan.

Alas, with insert ....select this is not the case.

Even if I try to work with inline views: no effect: