The only thing I can think of is I have open ports going to the corporate lan. I know it should make no difference but the Draytek does seem to have a few quirks, so it might be worth checking around that. I say this as your lan is stable then fails for no reason, it could be an incoming call (unsolicited) which is causing these random drops??? All my DOS is turned off etc, for no reason other than when I had the problem of connecting (using the wrong email address :? I got desperate and turned everything off)