That's pretty weird. I guess its not your ps3 ethernets fault then. It must be your ps3 that for some reason screwd up the network settings or your router screwd up with the ps3's mac address with the routing table, or something like that.
Try setting your network settings manually on your ps3.
If  you don't know or this does not work maybe you should try and restoring your ps3 at its default settings. I don't know if it will delete any of psn settings, i've never done it before.

Before you try any of these, unplug your router and modem for at least a minute, if you haven't tried this before.
I hope you find a solution

I called our ISP and they restarted the servers and it works now! :D

No idea what the fk happend. Thanks for the help guys!

Anytime man. Glad things started working. =)

i have problems with my ps3's online, but thats mostly because of my internet sucks.