1) At some hours of the day the uploading works just fine, at some hours it doesn't (and we can't figure out regularities in the hour patterns). The tests are done using the same ISP
, OS, and browser for consistency.
2) On Chrome from iOS users see this error: http://imgur.com/48kwWn2
3) When the user uses VPN, it works (but uploading with VPN is slow and they prefer not to do it.)
Any hint is appreciated.