MacBooks disconnect from Wi-Fi because of iPhone 4S - how to fix it?

[Freezorro]

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?

 

[Weaselboy]

It sounds like his phone is grabbing the DHCP IP being used by your Mac. When this happens, can you get your Mac on the Internet again by forcing a DHCP IP renew? Go to Network in System Prefs then in Advanced click renew DHCP address.