Verizon Jetpack 7730L

I never claimed it would do wonders but it doesn't cost much and it's done a good job for me. It's worth a try. If it doesn't do the job you need done, then you can go to the trouble of mounting a whip or a highly directional yagi or what ever floats your boat. This one's easy to stick on a window, plug in to the Jetpack and improves the signal strength.

Here's one for just over $12 on Ebay right now if you're willing to wait a couple of weeks for it to arrive from China.
https://www.ebay.com/itm/35dBi-Signal-Amplifier-4G-3G-Broadband-Mobile-External-Antenna-LTE-HUAWEI-TS9/173288984883