Dear Ulrike,
> You could try with \usepackage[pdfa]{hyperref}. It sets a flag
> to
> links which seems to tell ghostscript to keep the links
> (untested).
>
> See also https://github.com/ho-tex/hyperref/issues/74.
That works perfectly, thank you!
Now when I use ghostscript to compress my pdf, all the links
work. Thanks very much! :)
Daniel