I gave my friend my ATT Samsung S7 Edge. I first had it unlocked. We then took it to the store, and they activated it with a SIM. She can make phone calls, text, and use her home Wi-Fi, but she soon discovered she cannot connect to the internet outside her home. We took it to the store again, and they put the SIM in another phone, and it worked. Store employees called tech support and could not get it to work. I called tech support, and they had me manually put in Access Point Names (erc.tmoble.com and fast.t-mobile.com). Neither APN worked--although we did get a 4G symbol. I will add the phone has the latest ATT version of Nougat. It has been over 2 weeks, and she still cannot use mobile data, and no one seems to know why!!! I suggested she leave T-Mobile for ATT as it is an ATT phone, but she likes T-Mobile. Anyone have any suggestions. The only thing I can think of is going back to her Note 3, or possible doing a factory reset.
Best answer by magenta1556610
I had a similar situation with a recently unlocked AT&T Samsung S7 (Model: SM-G930AZDAATT) on Android 7.0. When I initially inserted the nano SIM card the mobile network worked just fine (I was even able to use the phone as a mobile hotspot for my laptop), but suddenly the mobile data didn't work. Long story short here is what I did.
I went to Settings --> Connections --> Mobile networks --> Access Point Names, pressed the three dots on the top right, and selected "Reset to default." The phone did its thing and then a bunch of APNs showed up (I had originally deleted all APNs except the T-mobile APN). One of those APNs was called "T-Mobile GPRS" and it had "fast.t-mobile.com" underneath it. I selected it and in the "Edit Access Point" screen I changed the "Name" from "T-Mobile GPRS" to "T-Mobile." Then, under "MMSC" I typed "http://mms.msg.eng.t-mobile.com/mms/wapenc". Next, under "APN type" I changed the text from "default,supl" to "default,supl,mms". Finally, I pressed the three dots on the top right, selected "Save", and restarted the phone. When the phone rebooted the mobile data worked. I realize that most of what I wrote is already documented elsewhere ( Generic T-Mobile data settings under "Android APN settings"), but I think the difference for me was resetting the default APNs which I described at the beginning of this paragraph and then following the procedure in T-Mobile's Generic data settings support page.
I also noticed that after the phone rebooted an APN called "T-Mobile MMS" showed up in the list. This is likely to be because of what I typed under MMSC and/or APN type. Anyway... In summary, here is my APN configuration (which at the time of this writing I have mobile data working):
Proxy: Not set
Port: Not set
Username: Not set
Password: Not set
Server: Not set
Multimedia message proxy: Not set
Multimedia message port: Not set
Authentication type: Not set
APN type: default,supl,mms
APN protocol: IPv6
APN roaming protocol: IPv4
Turn APN on/off: APN turned on (this is grayed out)
Mobile virtual network operator type: None
Mobile virtual network operator value: Not set (this is grayed out)