Well, I use Wireless and Wired - alternating depending on my connectivity.
To connect your wired you need to go to Internet Settings then custom or manual (which ever one its called) and choose wired connection.
Fill in your details following the steps provided.
If that doesn't work go back to easy setup and it should already have the wired selected.
If that still doesnt work, try unplugging your ethernet cable at your computer and your ps3 alternately.
If that still doesnt work for you , ummmmm I dont really know. Try googling it and if you cant find anything call Sony.
My PSN is Maccaz15. Add me as a friend if you ever get on again.