If for some reason you can’t go online or applications that need the internet are not working you can try this solution. If you formatted your phone or flushed a custom ROM or change some settings and got the problem, this should help. I found this solution here : forum.vodafone.co.uk All the credit goes to Northern-dj for helping. I am posting this so you could find this solution on youtube and to show you step by step what to do.
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Galaxy s2 (II) – can’t go online / unable to connect to network