Why does my PS3 hate my Broadband connection?

Hey Everybody,

Ok, so for some time now I have had troubles with intermittent disconnects and general slowness on the Playstation Network. I assumed it was the router and port forwarded it.
No luck.
I disconnected the wireless router (Apple Airport Extreme n) and connected the PS3 straight into the cable modem (I have Road Runner)
No luck.
I bought a new PS3 slim and did all the above to it as well.
No luck. and no different than my other PS3 (I’m returning the new one today)

Aside from what I’ve already done, I’m at a loss of where to go next.

As of Right now, I can connect to PSN, download games, update the console, play lighter online games (Fat Princess is semi-stable but I do get booted quite a bit) But if I try to connect to say Uncharted 2’s multiplayer, it tries for 10 mins and fails.

I’d also like to point out that I haven’t had any other problems with any other device on the network, this being the computers, Wii, and Xbox 360 (both of which nave no problems playing games online.) I just checked my bandwidth it’s 6260 kbps download, and 50 kbps upload.

I’m at my wits end with all this… Fluther HELP!