Apple Tv

So I just got this internet with T-Mobile however when connecting to my Apple TV device it says wrong password and I can't change it log in to it or say forget network bc there's not an option. I just see wrong password and then (-100) what to do next. I've already co reacted apple on twitter and T-Mobile have been super duper helpful. I can tether my phone but I don't wanna exceed my data. Help. Thanks