I have tried to download free gift checklists/PDF files from several different sources (ex Miracle Morning, some author websites, Goodreads) and they never work correctly. I can look at them and then after a second the image disappears from the screen. And whatever downloads, I can't open it on my phone at all. I am able to download and open PDFs from all other sources. PDFs shared via Dropbox are the only problem.
I don't use any browser except what's on my mobile device because I don't have any other browsers. I always have to go to a computer. I will never share files on Dropbox thanks to this experience that affects everyone with an Android. Dropbox mobile is broken.