@AndreasNiedermann, after looking at some of the recent requests you made (the last appear to have been on September 3), I have some observations.
Many of your requests were made with an ident argument containing “=0” appended to them. For example: “LH177=0”, “DLH177=0”, and “DLH1125=0”. I would expect all of those requests to fail or return no results.
Most of your requests were made with a “howMany” argument of just 1 (or in a couple of cases, 5 was supplied). The server-side implementation is to take the max() of the following three values: the howMany argument for that call, value that last supplied to SetMaximumResultSize, or 15 if you have never called SetMaximumResultSize. I can confirm that your SetMaximumResultSize of 1000 was received.
If you are not receiving the expected number of results then it is likely because the “howMany” argument is not being passed or encoded to us properly. Pasting the full URL and arguments that you are requesting might allow further debugging.