Hi Felix,
Thank you very much. I did not expect this, but indeed the problem is the browser. I use Firefox as default browser (on Windows 11). I switched to MIcrosoft Edge for this and it works.
Any idea what the reason is? I presume some extra bytes transferred, but why. Or/and is it about the way the webserver handles it?
It took me quite some time and could take me much more time without your solution!
Thanks again,
Kees