I'm an end user, not ea / bioware staff.
helpful information for future reference:
internet connection type and speed
computer specs (cpu, ram, video card)
now, if you have the same origin account loaded on multiple computers, you need to make sure that the secondary computers are not logged into origin with the same id.
if you verify that origin is not active on any other pc with your account, verify that you can login to your bioware account
social.bioware.com
your origin account
store.origin.com
and if needed your ea account
those servers are for the U.S., you say you are Italian, but do not say if you are trying to connect from Italy, so i can't give you the direct addresses for your local country.
if your account is good, and no other computer is connected with your Origin ID, i would uninstall, then reinstall in this order:
origin client
game base platform via origin NOT previous media. (make sure you can connect to multiplayer after install)
If you still cannot connect you do either have a problem with your computer, your networking equipment, or your account has been banned.
If you can connect, you can check what dlc you are authorized to use at
https://social.bioware.com/user_entitlements.php
then install any dlc. (i would re-download from that site to make sure the installer is not modified / corrupt.)
I would also advise only installing one dlc at a time and then reconnecting in case it is a problem with a single dlc.
when in doubt
http://www.bleepingcomputer.com/download/combofix/
Exploding_Idiot, Security+, MSCE
