Another issue I remember having on my laptop/win10 is if I had more than two usb cables plugged in to the laptop it would kick the fiber dongle off line.
For example I have a dye sub printer usb cable, wireless mouse usb plug, HDMI to a remote monitor and the fiber usb cable plugged in. It will always drop out the fiber usb and give me a "dog not found" message. If I unplug the usb printer it will find the fiber usb. I can watch it under windows devices as it pops in and out as a usb device.
Also, does your ezcad still boot up under demo mode even though it does not find the dongle? It should still run even with no laser connected to the system under demo mode.
Another quark I have seen is once the "dog is not found" it sometimes requires the computer to do a hard shutdown.
Sequence is turn on laser first (key lock, master switch and then laser switch) and then turn on the laptop.
These are all random notes from when I first set mine up.