The previous Cradlepoint firmware 1.8.0 is not work well specially for booth LG VL600 and Pantech UML-290 3G EVDO/LTE 4G usb modem. The most problems include, no connection and disconneted (but signal is Good) and display/indicator signal strength for Pantech UML 290.
Download new firmware (1.8.1) : CradlePoint Firmware 1.8.1 Download
Dowload release note firmware 1.8.1 (.PDF) : Copy and paste this link in your browser
http://cradlepoint.com/files/uploads/ReleaseNotesMBR1_8_1.pdf
The routers supported include : MBR1200, MBR1000, MBR900, CTR500, CBA250, CBA750, MBR800
This new firmware offers user to improve modem performance and added with new feature to select connections in 3G or 4G Lte only. So don't worry anymore about your 3G or 4G signal strength, especially when you are't in unstable 4G LTE coverage area, because it is usually the automatic mode will move around and this is what causes the connection is lost or missing altogether.