I am not sure about device modelBut stil i think that your device doesn't support dual band wifi , so its only can be connected with 2.4GhzKindly note most latest devices of Samsung come with this support
Okay , sometime other country devices are come with some pre loaded software for some sim specific devices like t mobileEg you brought a mobile from t mobile in finance then t mobile add some softwares in itSo please go to app list and check for this...