Straight Talk AT&T lte issue

[TacoCat is TacoCat]

So I got an unlocked BLU win Jr LTE and am using the AT&T sim from Straight Talk and transfer the account from my old phone. I can make calls and send/receive texts perfectly. I can even send MMS fairly well too. But the data is where the problem is. I only get data services at my house. Anywhere else, nothing. I usually have a decent signal and It shows either "AT&T LTE" or "HOME LTE." I tried testing it with the speed test.net app and it shows no download whatsoever but the upload speed is great. I just don't understand why it only works when I'm at home.