Decided to upgrade the Cayman 3366-ENT ADSL Gateway from Netopia, currently hosting the public link for the Thilelli.NET Project. All went smooth and well. The gateway is now at the latest firmware level available (8.5.0 at the time of this writing).
At the same time, try to avoid some recurrent problem on the link (seems ok but doesn't let real traffic to pass through it) helped by the 24-Hour Scheduled Connection procedure. Waiting to see if it really works for our site... thanks to our ISP for providing a nice administration and status page.