External here more likely refers to the fact that you should not use a proxy managed within the rancher environment, like the internal HA proxy service that you can configure for your applications (see Adding a Load Balancer). If your load balancer was offline it would be difficult getting it online again, if you can’t get to rancher, because the load balancer is offline.
Any decent load balancer managed outside of your rancher environment should be fine.
The servers are created successfully in the cluster and also able to access using individual ip, however unable to access it using LB ip.
2017-09-11 13:29:08,944 INFO [pool-3-thread-1] [ConsoleStatus] Cluster membership changed [rancherserver1:9345, rancherserver2:9345]
The backends shouldn’t have ssl. You’re telling HAProxy to open a SSL connection to the plain http 8080 port (and remapping that to 443, which is OK but confusing).