Whenever I try to view a file someone has sent me, the Dropbox app in my phone (Android, Samsung Galaxy S9+) says "couldn't connect to DropBox, please check your internet connection". I have internet connection (I've tried it with full LTE bars and with full wi-fi), but it still gives me the message and won't allow me to view the files. I've gone to the "Apps" area of my settings and have made sure the DeopBox app has all permissions. Any ideas about what could be causing this?