What I have taken the message as (And don't quote me because I am just purely guessing)
Is that due to E being an https site, if the wifi is not reliable or a password protected wifi, perhaps it (the browser) is worried that your passwords/information can be stolen. Because like others have mentioned, other websites are fine (I am guessing they are normal http sites). Perhaps that is why you are unable to connect because I get that message and I use the internet on my android (so not Safari)
Again, I am just making an educated guess.