It depends on the distance between you and the antenna of the 3/4G provider. If it is close enough, the Netgear antenna will not make much difference. If the distance is great, it can improve the reception. But it can't change the speed.

Hello, I bought such an antenna to install in a cottage. I have noticed a better signal reception. However, I don't have the impression that the speed is improved.
Good day to you. Joseph Darbellay