Strict nat type needs to change to open

Which AT&T Internet service do you have?

HERE is a great tutorial one of our forum members created last year on getting the Xbox NAT set up correctly.

I use the mobile internet box from att and when I enter http://192.168.1.254 it  doesn’t do anything it just says this site can’t be reached 

I'm guessing "mobile internet box" means some sort of hotspot, which doesn't have the capability to do what you need to do.