Appian 18.3 is not routing the call back to NGINX

Question

We have setup Appian 18.3 in AWS with Nginx frontend. The call to Suite is working fine. However the authentication is failing and access denied and redirecting the calls to 80 instead of 443

2018-10-29 16:36:27.448 INFO [http-nio-8080-exec-1] org.apache.catalina.core.StandardWrapperValve.invoke 2018-10-29 16:36:27,447 [http-nio-8080-exec-1] ERROR com.appiancorp.security.cors.CorsFilter - CORS request rejected; invalid request from <IP> to /auth

javax.servlet.ServletException: CORS origin denied <Cloudfront url> not on allowed list:[]
        at com.appiancorp.security.cors.CorsFilter.handleNormalRequest(CorsFilter.java:314)
        at com.appiancorp.security.cors.CorsFilter.doFilter(CorsFilter.java:278)
        at com.appiancorp.security.cors.CorsFilter.doFilter(CorsFilter.java:227)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at com.appiancorp.security.auth.logging.AuthenticationLoggingFilter.doFilter(AuthenticationLoggingFilter.java:37)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at com.appiancorp.security.auth.AuthProviderFilter.doFilter(AuthProviderFilter.java:80)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)