I'm having similar problems west of Charlotte, NC. Using a UML290 modem for about 1.5 years. I had settled to the point where I was averaging 11M up and down and suddenly I'm lucky to get 3M down. I've been through Sprint, Millenicom, now VZW, 6 or 7 antennas/gids/yagis and several modems over the last 4 years so I've become a wireless data expert in self defense. I mention this because when I call support, they only want to troubleshoot my end even though nothing changes (other than firmware).