PS3 won't/can't obtain IP address?

I had the same issue so what i did was this:

Before you do it, switch off your router and wait for about a minute, then restart it.

a) instead of selecting easy choose custom when on connection settings

b) scan through and do not make any changes allowing it to select everything automatically

c) when going through the connections let it check your DNS server, I.P address automatically

check connection settings and your done

the difference is most people select easy, but in this case you need to select custom and go through the options without making any changes

just a long winded way of doing it but worked for me, it may not work for all off you but worth a try i suppose.

Other than this, you could try using a static IP adress, and make sure you have UPnP enabled in your router. hope this helps you :)