Cannot login to website on iPad

My elderly father has an iPad mini and he cannot login to his utility and sky websites (where he has to use password).

he took it to Genius Bar where is was" reset" but problem persists.

i Have managed (via FaceTime with him) to establish

hhe can login into sky account via sky app, or via google app but not via safari. When he enters username and password on any safari site it jousts refreshes back to login screen.

please help.