If your device has lost WiFi connection, it will normally reconnect, but if it doesn't then please recycle the power as follows:

Unplug the power for the Nexx device, wait 5 seconds, and plug the power cord back into the outlet.

 Also, check to see if you are on the latest firmware:

1.   Log out of the app.

2.  Log back in.

3.  Go to menu->about device, tap "Upgrade firmware".