For 3gs new bootroom(MC model), you cannot downgrade unless you save your phone shsh 3.1.3 with cydia. The reason is apple no longer signing firmware lower than 4.0.2. To solve your network problems, try reset network setting. Hopefully it will work.
however, if your 3gs is old bootrom than you can downgrade to lower firmware.
DiGi iPhone Discussion Thread | V2, Strictly Booking/Buying Discussion Only
Aug 20 2010, 06:12 PM
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