Netgear combo modem/routers mess up the whole gaming thing too. Best solution I can offer is to hook up a standard modem (not converged w/mta or wireless) and then connect to a linksys(or other reputable brand) wireless router then to the ps3. I believe the issue has something to do with NAT and port forwarding. There is a work around with the netgears but it is a huge pain in the butt to set up.
This is CABL.com posting #322430. Tiny Link: cabl.co/mbv2E