if u have an old style modem then just plug it straight in to ur ps3 dont use a router as a router will try sending packets to all ur stuff u run on the router and store all the cashese there is sent and slow down the sending of the packets witch causes lag
so if u have a old style modem that is just a modem not a modem and router built as one it needs to be just a old modem with just pluged straight into the ps3 this will solve most of the problems wit lag i done this last night and my good i was going 30/6 in most games compared to my usual 12 /18 so if u guys have a modem and router separate then just use the modem while playing the game if u can

I bought a modem router combo. Love it better than the other way

well as my moden is right next to my ps3 its easy just to plug the modem straight into my ps3

Yes this works been doing it since MW3 my stuff is right next to my PS3

I run wirelessly most of the time since my router is in a different room. You know I actually bought a dual band router hoping to run my PS3 on it's own 5.0 ghz frequency and run everything else on the 2.4ghz. Then when I tried to get it to work I quickly found out the ps3 isn't compatible to the 5.0 frequency! Man I was bummed!