Firefox android works correctly in both modes.
I cleared the cache and tried two browsers – Chrome and Opera. The same thing – in portrait mode, the download sometimes works, sometimes it stops completely. At Chrome – if I turn off the device screen and then turn it on, the download will immediately work until the next post – same at two devices. In the Opera, turning off the screen does not help.
In landscape mode, loading works without problems. Turning off / off caching plugins does not affect anything. I made several screen capturing, I’ll upload them soon.