I already connect to the internet using a modem SmartFren CE628 but I have not been able to access the internet.
For example ping 8.8.8.8
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I had similar issue, don't know how to solve it permanently, but what I do to connect to the internet is going to System Settings -> Network -> Mobile Network[or sth like that, I don't have english software], then in the select you choose to add new connection proceed normally. It should connect to the internet, and you should be able to ping 8.8.8.8