Why do I have so much trouble downloading game updates for PS3?

I only have trouble with my PS3 internet connection when I'm trying to download updates, either for the system or for games like DC Universe Online. I can get signed in, I can access the Playstation store, I can access Netflix. But whenever I try to download the automatic updates, it'll give me 1%, then the time remaining just keeps on climbing. I've been able to get updates, but it honestly just feels like, at those times, I just lucked out and it downloaded. I know it isn't a problem with my internet since the connection to my PC works fine. I have a wired connection to both the PS3 and the PC. Please don't tell me to reboot my modem and go from there, because I do that about half a dozen times every time I try to get these updates. It never has any effect whatsoever. It's really frustrating, especially on a game like DCUO that I'm paying a monthly fee to play, but can't play if the latest software update won't download. Please help!