Go to your LW menu Tools>Options>Advanced>Firewalls & tick UPnP & press Apply. See if this makes any difference.
I have to say if your 6346 test was kaotic then that itself doesn't look good!
I saw
this & just hope it doesn't apply to your isp.
If all the above doesn't work are you willing to try an experiment?
See:
http://www.gnutellaforums.com/showth...threadid=32882 & apply Sock 5 under Tools>Options>Advanced>Proxy. I'd like to know whether this makes any difference. I can't find anything on the web about your isp blocking but I found indirect references to filtering. That means I don't know for sure ... just some principles they use that brings me to the possibility. This means you could be the test case for the isp. It's not so hard to do or to change back ... But you may need to make some other small adjustments with other sttings I don't know. Proxy I don't know about. Except from some pm's I've received from the author of the link I gave.
You don't have control over the devices. Hopoefully they are UPnP compatible.