When you do ADS connection test from transaction code SM59, you are getting test result status of HTTP responses like,403 /404 /405 /500

As per SAP Note 1177315 – ADS RFC destination test return 403 / 404 / 405 / 500 code.

You can ignore these 403 / 404 / 405 / 500 HTTP return code. Even if these HTTP code is returned from SM59 connection test, ADS functionality works without any problem.

You should execute ABAP report FP_PDF_TEST_00 instead of using SM59 connection test.