Well, thank you but I usually disconnect because of my crappy winmodem and not 'cause my ISP (but I can't connect faster than 50666bps, I think is 'cause of the line noise).
Close and restart, ok, that's what I do normally. But, is that the only solution? Isn't this problem a bug?

About connect manually I write on connections the server and click on add but nothing happens (it is not added), anyway I click on connect and not a thing happens either.