So everything works perfect, than my brother comes home with his iPhone 4S, iPhone automatically connects to Wi-Fi, and all the network is down. When he turns off Wi-Fi on his phone, everything is fine again. The problem occurs on all Macs at home. My iPhone 4 (not 4S) doesn't do that. Both iPhones have the newest iOS update 6something, I have MacOS 10.8, my bro has 10.7. I heard this problem occurs more often in many places. Haven't found solution. Any ideas?