Connection error when the app is deployed on the web server - BoxJWTAuth, .net SDK

My intranet .net application works fine in visual studio. But when I deployed it on the web server I am getting the following error.

No connection could be made because the target machine actively refused it

Since it is an intranet application it is deployed without SSL. It looks like that application setup on the Box end accepts only https:\\.... for redirect_uri except for localhost.
Does this mean that I have to install SSL certificates for my intranet application in order to access Box APIs?