Battlefield 3 MultiPlayer Problem: Game disconnected: could not join server.

I solved a few months ago by checking properties on the control panel of windows (mine is w7):

My problem was in particular the fact that I shared the connection of a modem thought my wireless card in order to make another pc able to have internet connection. I solved by simply deleting ALL the services ports that are Here.
This was the solution that worked for me, I don't know even why but if you are out of ideas better try this workaround.
Sorry my english but I'm Italian.
bye