I've tried loading a dynamic PDF on several mobile devices, all of which fail - primarily I believe because there is no .PDF extension on the file. However on a desktop machine, it downloads without issue. Here's how the URL looks (it won't work here because it's dynamically created, but just to get an idea of how it looks):
Any idea what needs to be done here? I'm thinking some kind of mobile device-specified doc type so the phones know it's a PDF. The file starts to download, then after several minutes, simply fails.