I´ve the MiFi Router and problems when the 4G Module is connected.
The problem is, that the router reboots all the time.
Sometimes it is active for a couple of minutes, but then it reboots again.
Or the configred WiFi network is not even getting up, so I can´t connect to the router.
I think that is not happing when the 4G module is deactivated / not connected.