update ios iphone 4s

I tried to update my iphone 4s to ios 9. While going through the proces, halfway my mac gives an error 50.I can't restore nothing. My iphone gives the pic of needing to be connected with itunes now. When i do this i get the message 'restore' . When i do this it gives me the error 50 again. I tried a new dock connector, another comp with the latest itunes, a new cable, tried to reset it, tried the CPU mode, shut of my firewal, even tried the changing in the terminal... everything. Can someone please help me!?