BMW X1 (2012) GSM problem

Hay guys and I am new to bimmerpost (from Croatia- BMW X1 2012), and I have a problem with a weird problem with mobile data connection. When it defaults to 4G it shows a full signal but no internet connection, but when I put it on the preferred 2G, the 3G signal of the connection is weaker but the internet connection works ... Please help what to do to have internet on 4G. Thanks a lot for the answers ..

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  dpurgar3