Try this… power cycle the Jetpack and hardware reset it. Power off the Jetpack, remove the SIM card, power on the Jetpack, wait two minutes and power off the Jetpack. Reinstall the SIM card and power on the Jetpack. Also, try different locations; you may have a weak signal and strong source of RFI in the area. RFI can affect both radios in the Jetpack as well as the Wi-Fi radio in computers, so try changing the Wi-Fi channel in the Jetpack to 1, 6 or 11, because one often works best. Lastly, maybe the device is defective. If under warranty, take it to the Verizon Store and complain about a weak signal. Good Luck and the device actually does work.
If you are in a full service area then your download speed should be between 5-12 Mbps on the VZW 4G LTE network and 1-3 Mbps on 3G.
To find your download speed you need to visit a speed test website such as www.speedtest.net. Run the test a few times in the same location to get a good average then move to a new location. Try to sample your speeds both inside and outside your home to get a good comparison. It can also help you sample speeds on the side of your house that is facing the local VZW towers and then on the opposite side of the house too. A final good test to run is traveling to a different site that preferably runs on different towers and compare those results to those of your own local tower.
This process of sampling speeds is known as a site survey. Site surveys will help you reveal any dead spots in your environment so that you can determine if boosters or a quick rearrangement are necessary to improve your results.
More info on site surveys:
More info on cell tower locations: