I had a similar problem. I just hooked mine all up tonight. After lots of resetting the device I can connect to the public FON_AP and even login. (Although it's incredibly slow. Like 9600 baud slow.)

 So I register it and I switch to the MyPlace private connection. Connects no problem. Grabs an IP. If I ping the gateway IP continuously it gets about 50-100% packet loss. About 2% (literally) of the time I can pull up one of it's internal configuration pages but I can't get anywhere on the public network.

FON_AP disappears, unplug/replug no go. Fire up netstumbler and hit the hard reset on the bottom with an ink pen and repeat the above to no avail. I then shutdown all my other wireless devices but it made no difference. It's not a signal strength problem. I can be two feet away with no difference.

I sent them an email and I'm curious what they come back with.