Can't find Wifi

Dec 4, 2013
I use stable 4.0 miui rom , Use wifi at home that's all right work good, but I went to my friend home, he use vodafone wifi rounter and I can't see wifi hotspot from friend's wifi rounter. Not just at my friend home, my another friend home use the same rounter and I got same problem. What? Can please anyone suggest to solve this problem. thank