George,
We've received a few reports of this issue over the past couple of years specifically between iFly units and Echos. As I understand it, the message box is the only symptom the wifi remains connected and you still are getting data.
We've had a couple customers send their iFly unit to us, we connected to an Echo in our office and left it there for days, tried a variety of connecting other devices to the echo, etc. Never been able to duplicate the issue. It might be related to some sensitivity to noise in the cockpit, or something specific to your Echo, or some incompatibility between the devices. We've also spoken with uAvionix, they did have an update to the wifi firmware but it was like 2 years ago. You might check with them to see if your unit has that update.
Sorry we cannot help more with this issue, I understand the popup can be irritating.
-Walter