Yeah, for some reason Soul Caliber IV has been having problems. Expect to see a patch for it soon. In the mean time, double check that all the needed ports are forwarded for the PS3. Here's the current list for all the PS3 stuff. When doing port forwarding, under tcp/udp options, always choose "both"
Do you have DMZ enabled on your router? If so, turn it off. From what I've read, this is the most common cause of the error. I have no clue why this would cause an error with something not under DMZ, but it seems to fix it for some.
Well, if it has been on going all day, I would contact sony support, as it doesn't seem to be a router issue, and sounds more like a server issue to me (or it's a port issue we aren't aware of yet, as this also happens with SCIV).
Please let me know what the outcome is (via private message would be best, so I don't miss it).