about the external address, i know it because i use my mobile connection also to connect my laptop (tethering?), and HFS passes the self-test this way.
i guess i get the same address on the mobile phone, although i'm not sure.
i didn't say i don't get disconnected, but not in a short time. I say it by the connection indicator in the top left (i have a nokia). Some details: a year ago, all worked fine, and closing the last internet application automatically caused the connection to be closed. Since some time, this is no more, sadly, and i have to close the connection manually. (luckily there's a decent shortcut for it). This way, sometimes i find my phone connected with no internet application open since long, and my battery clearly wasted and the phone warmer than usual.
This may not be a scientific proof, but it's surely suggesting what i stated, don't you think?