I've been having the same problem for the longest time. I called Sony about the issue and they wanted to go over some troubleshooting steps with me that included going into my router settings via the PC. That didn't work. So I finally started looking for information online as well as asking a few friends from other message boards about this problem. I finally came across this page noting about the Media Server being turned off. I'm going to attempt this now and see if it works for me. I've been playing Call of Duty: Black Ops and I basically get kicked out of every match after It's done. It's rediculous, I wanna stay in the same room, especially if everyone I'm playing is bad. I'll post here again to let you know how things went though. Wish me luck!
Well I tried disabling the Media Sharing Center. How can I say this..It worked and it didn't work. I don't really have a problem signing into the PSN (other than from time to time I get a DNS error). So disabling the Media Sharing Center really didn't change anything. I still randomly get kicked out of rooms in Black Ops, while the rest of my party stays in the room with no problems. I'm always having an issue playing Black Ops in my garage where I have to play from time to time when the TV downstairs is in use. We have an HDTV in our main garage and I'd love to be able to play on their at all times instead of downstairs. When I play late at night downstairs I have to keep the TV down because people are sleeping, and I can't talk loud either. That's going a little off topic though. Anyways, I think this issue is mainly to do with playing games online rather than the PSN itself. Why am I having trouble with being able to stay in one game room until I decide to leave? I'm basically being kicked out of the game lobby after every match and It's really irritating. Why can I connect to the PSN when I'm playing in the garage but I can't play any matches? Does that mean I'm having an issue with the game or the PSN? Like I said though, when I play downstairs no more than 10 feet away from the router wirelessly, I can connect to the PSN and play games no problem. However, I get kicked out of game lobbys after every match nine times out of ten. I haven't been able to test this with any other game, as I only have Call of Duty. Should I call Activision about this problem? Any answers would be greatly appreciated, I'll check back frequently until I get this issue resolved. Until then I guess I'll keep trying to call Playstation support and maybe even Activision.
If you haven't done so already, download and install the latest firmware for your router from the Linksys support site. I had a similar issue with the same router (mine is a 'Version 8'), but never had an issue connecting any other wifi device until I connected the PS3. The firmware release notes show that it "Resolves issue with UPnP" and "Resolves issue with router disconnecting from some particular online game servers", among other fixes that may or may not be relevant to your specific issue. There should be sufficient instructions on how to update the router's firmware on the Linksys support site. Also, you may want to backup your router's present settings (which I recommend doing prior to updating the firmware, so that you should at least be able to get the settings back to their present state if they are modified for some reason).