I am having issue connecting to the LTE network on AT&T. I went in setting>dual sim & mobile networks>network mode but it would not allow me to click the LTE priority (recommended) option. When I click on it, the phone automatically changes it back to 3G priority instantly. I just bought two S3 phones with two brand new SIM cards from AT&T but only one phone is giving me this issue. The other S3 phone picks up LTE just fine.