\includepdf seems remove internal links within included each PDF file. For example, in
\documentclass{article}
\usepackage{pdfpages}
\begin{document}
\includepdf[pages=-,fitpaper]{1.pdf}
\includepdf[pages=-,fitpaper]{2.pdf}
\end{document}
2.pdf has some internal links in some pages that, when clicked, will jump to some other pages.
after compiling the above latex code by pdflatex, the output pdf lose the internal links.
I followed https://tex.stackexchange.com/a/44104/861 using pax, but it doesn't seem to make the internal links work in my example. Am I missing something? For example, you can combine an arbitrary pdf, and a pdf generated from this webpage which contains internal links.
onimage.sty,pdftkandPerl: https://tex.stackexchange.com/a/423471 – AlexG Mar 28 '18 at 14:13