Cannot get my smarty to work in mt TP link M7350

AngelaK_2736537 You do not say whether you made the necessary change to the APN; if you did not then the sim will not connect your router.

Aa JJP2RidesAgain rightly says, a metal box (caravan) can act as a Faraday cage and block electromagnetic radiation (mobile signal in this case).

If you say that everyone suggests that is is simple, did you not also see the many examples of this problem and the responses?

The device you bought might be network locked, and if not locked to SMARTY it won't connect to the Internet using your SMARTY SIM, AngelaK_2736537.