Originally Posted by
SpookDroid Since you flashed software via ODIN you can't guarantee that the phone is 'OK'. I suggest to try factory resetting it (if still possible, haven't flashed in a while so not sure if doing so wipes the recovery partition) and testing WiFi out. If that still fails, check in different networks. Might be a 'problem' with your router (some routers needed a patch installed to play nice with some Samsung phones, or some units would have issues with WiFi in certain channels).
If this was a wifi channel problem the download speed would be affected too, wouldn't it? I did the odin flash after a few factory reset, trying a different router and even a hard reset. Nothing helped.