Can't login instagram via mobile

i can login via webstagram, statigram and instagram web viewer but i can't login on my android mobile phone. uninstalled, reinstalled, updated. still nothing. its not just my account. cant login my ​sister's account too. tried a friend's account also. it loads as if it's logging in, but it stops and stays at the login screen. no error message like "try again" or "change your passport" or "your account was disabled" my mind's blowned in the worst ways and i'm freaking out. any idea what's going on and how to fix it?

Nobody? ok.

Are you using any proxy on your device? Try turning it off.

No. I only use one account so I don't use proxy.

Did I mention I can't login to any IG accounts at all even via Bluestacks?