I have the exact same problem and have found that firmware turtle-3.bin will function as I expect. I also have the Lan Turtle 3G which was purchased about a week ago. I had to do the factory reset to get back to the working firmware and suspect that version was in the device when it arrived. I followed the instructions and upgraded the firmware which is where the Lan Turtle became useless. Why would turtle-4.bin and turtle-5.bin not work? What changed in them?