Just a FYI.. I am in the "Extended 4g" area according to Verizon's coverage maps. When I first got my Jetpack it would only lock on to a 3G signal, it would not find 4g at all. I already knew I had 4G service however because I have a 4G capable phone as well that did pick it up.
The only way I got the Jetpack to find 4G service was to switch it to LTE Only mode. Once I done it, after it rebooted it found 4G service with 3 bars steady. 15Mbps down/7Mbps up.
You can find this setting on the Jetpack's web interface. On the WWAN tab if I remember correctly. Change it to LTE Only and click Apply, it will reboot once you do this.