S7 from att with new t-mobile sim card. get and send calls and texts ok. Gets internet thru wifi. Cannot connect to network for data.

magenta5070430

    Got used S7 from son that was used on ATT.  He joined T-Mobile and put us on the family plan.  Install new T-Mobile sim card.  I can receive and send calls and texts ok.   I am able to get on the internet with wifi only.  When I shut off the wifi and try to connect to the network I get that I am offline or cannot connect to network.  Been through hours on the phone to T-Mobile and to their store many many times. Tried many different Access points with no luck.

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