In August of 2017 Vantiv (Litle) changed their endpoints. If you are running version 5.05 or newer you will already have the updated endpoints.
If you are on an older version of Chargent you can either update your current package or use the following endpoint override.
You will also need to add the Remote Site:
* Go under Setup and in the Quick find search type Remote Site
* Choose Remote Site Settings and click New Remote Site
* Add the following Remote Site URL https://transact.vantivcnp.com