New VPN makes internet unusable

Hi, ever since I started using the new VPN, internet slows down to a state that it is unworkable. News subscriptions, some banking apps that require 2 factor authentication will only work if the VPN is turned off. I have tried the trouble shooting and also reset my router. Does anyone know of a solution (for Macbook) that could remedy the situation? As it stands I have to turn the VPN off for many regularly used websites to work