Ive been having the same problem, i cant seem to get my internet connection to work either. I have my eithernet cable running straight from the modem to my PS3. I had everything set to automatic and enabled everything except for proxy because i dont have one. What can i do to fix it?
If it's cable internet, run the cable to the modem, then run a cord to a router. From the router you can connect your PS3 plus any additional computers you want to access the internet. Your modem may not be recognizing the ps3 for whatever reason. Routers can run you roughly $40-$100 depending on the type you purchase.